Personalized myeloma detection

ABSTRACT

Disclosed herein is a personalized method for monitoring a condition or disorder associated with antibody production in a subject. The method can involve treating a biological sample comprising immunoglobulin from the subject to enzymatically cleave a target immunoglobulin associated with the PCD into one or more variable domain peptide fragments of the target immunoglobulin, and then measuring the one or more variable domain peptide fragments in the sample by quantitative mass spectrometry to quantify the amount of the target immunoglobulin in the sample.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No. 61/946,629, filed Feb. 28, 2014, which is hereby incorporated herein by reference in its entirety.

BACKGROUND

Multiple myeloma (MM) is a plasma cell cancer characterized by bone marrow clonal plasmacytosis, monoclonal immunoglobulin expression in the serum and/or urine, lytic bone lesions, hypercalcemia, anemia, and renal failure. MM patients initially respond to therapy, but relapse with drug-resistant disease. Therefore, early detection and effective monitoring are critical for management of MM patients. Current clinical assays focus on detection and quantification of the monoclonal immunoglobulin (or M-protein) secreted by the tumor cells, which is essential for diagnosis and monitoring of patients with MM and other plasma cell dyscrasias (PCD). The Durie and Salmon staging system and the International Staging System (ISS) are based on the correlation between the expression of the monoclonal immunoglobulin and the disease burden. The International Myeloma Working Group guidelines also describe the assessment of treatment outcomes based on the changes in expression of the M-protein. Patient monitoring strategies present significant challenges, particularly in the diagnosis of premalignant monoclonal gammopathy of undetermined significance (MGUS), prediction of progression from MGUS to MM, assessment of response to therapy, and detection of relapse.

Evaluation of disease is accomplished by serial measurements of the M-protein in serum and urine using a variety of techniques (Berth M, et al Clin Chem 1999, 45, 309-10; French MAH, et al Clin Exp Immunol 1984, 56, 473-5; Haraldsson A, et al Ann Clin Biochem 1991, 28, 461-66; Chen K, et al Nephrology 2005, 10, 594-596; Buckley R, et al J Clin Invest 1975, 55, 157-65; Hunder G, et al Arthritis Rheum 1974, 17, 955-63). Typically, initial measurements are made using serum protein electrophoresis (SPEP), which is limited in sensitivity to approximately 0.1 gram per deciliter (g/dl) (O'Connell T X, et al Am Fam Phys 2005, 71, 105-112). The monoclonal immunoglobulin produced in high concentration by MM cells can be visualized as a narrow, discrete, dark band usually in the γ region of the gel or electropherogram. SPEP densitometry and total serum protein concentration are used to estimate the amount of the immunoglobulin secreted by the tumor. Patients can be further characterized using immunofixation electrophoresis (IFE). IFE screens test for immunoglobulin G, A, and M heavy chains, as well as kappa (κ) and lambda (λ) light chains. Immunoglobulin D and E myelomas are rare; when suspected, IFE is repeated to detect IgD or IgE. The combination of SPEP and IFE establishes an estimated level in the serum and type of the immunoglobulin that is secreted by the tumor. These traditionally gel-based techniques have recently been replaced by capillary array instruments (Jolliff C R, et al Electrophoresis 1997, 18, 1781-4). For immunoglobulin heavy chains with high expression, SPEP is the current clinical standard for detecting tumor burden, because the disease-specific immunoglobulin is directly monitored.

However, several factors limit SPEP in monitoring tumor burden in patients (Morita K, et al Clin Lab 2004, 50, 415-18; Schreiber W E, et al Am J Clin Pathol 1992, 97, 610-13). Therefore, quantification of the involved immunoglobulin by nephelometry is also used to monitor tumor burden (Clark R, et al Electrophoresis 1998, 19, 2479-84), and it has particular value for immunoglobulins with lower abundances in serum (e.g. IgD and IgE), particularly because the background expression of these immunoglobulins is low. Serum free light chain assays (SFLC) are also implemented using nephelometry to provide an expression ratio between the light chains, which supplements other techniques for the detection of light chain only disease (Jagannath S Clin Lymphoma Myeloma 2007, 7, 518-23; Tate J R, et al Clin Chim Acta 2007, 376, 30-6; Pika T, et al Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2008, 152, 61-4). Antibody-based methods for protein quantification are also influenced by the complexity of the immunoglobulin system of the biologically derived antiserum and variation in its reactivity, as well as changes in the levels of proteins in the standard reagents (typically pooled serum) (Reimer C B, et al Clin Chem 1976, 22, 577-82). The presence of immunological subclasses (i.e. IgG1-4 and IgA1-2) also adds to the complexity of the analysis (Reimer C B, et al Clin Chem 1976, 22, 577-82).

Minimal residual disease (MRD) is the name given to small numbers of leukaemic cells that remain in the patient during treatment, or after treatment when the patient is in remission. It is the major cause of relapse in cancer and leukaemia. However, conventional SPEP is not sufficiently effective for detecting MRD.

A quantitative proteomic assay personalized for an individual patient and useful for direct measurement of the disease-specific immunoglobulin would significantly increase the sensitivity of detection over SPEP and allow for detection of MRD so treatment can be altered.

SUMMARY

Disclosed herein is a personalized method for monitoring a condition or disorder associated with antibody production in a subject. In particular, the method can be used to monitor a plasma cell dyscrasia (PCD) in a subject. The method can involve treating a biological sample comprising immunoglobulin from the subject to enzymatically cleave a target immunoglobulin associated with the PCD into one or more variable domain peptide fragments of the target immunoglobulin. The method can further involve measuring the one or more variable domain peptide fragments in the sample by quantitative mass spectrometry to quantify the amount of the target immunoglobulin in the sample. In some embodiments, PCD is monitored in the subject by the amount of the target immunoglobulin in the sample.

The disclosed method is personalized in that variable domain peptide fragments unique to the specific target immunoglobulin associated with PCD in the subject can be used. Therefore, in some embodiments, the method first involves identifying variable domain peptide fragments that can be used to quantify the target immunoglobulin in the subject. This method can involve determining the amino acid sequence of the target immunoglobulin and then identifying in silico one or more variable domain peptide fragments formed by enzymatic digestion of the target immunoglobulin that can be used in the disclosed methods. For example, these peptides preferably contain an amino acid sequences from the variable domain of the target immunoglobulin that is sufficiently unique to distinguish the target immunoglobulin from other immunoglobulin in the biological sample. For example, the one or more variable domain peptides fragments can contain the complementarity defining region (CDR) of the target immunoglobulin. In addition, the variable domain peptides should also be detectable by a mass spectrometer.

The amino acid sequence of the target immunoglobulin can be determined either from the immunoglobulin protein, e.g., isolated from the blood or urine, or from mRNA isolated from isolated plasma cells, e.g., from the bone marrow. In some embodiments, the method involves RNA-sequencing immunoglobulin mRNA from a plasma cell of the subject that is associated with the PCD. This RNA sequence can then be in silico translated into protein to determine the amino acid sequence. In some embodiments, 5′ rapid amplification of cDNA ends (RACE) is used to sequence the target immunoglobulin. Primers can be developed against the constant region of the immunoglobulin (toward the C-terminus of the protein) so that the variable region can then be sequenced by reading back to the 5′ end of the RNA.

The disclosed method can be used to detect any class of immunoglobulin involved in a PCD. For example, the variable domain peptides can be from a human heavy chain of IgG1-4, IgA1-2, IgM, IgD, or IgE. The variable domain peptides can be from a human kappa light chain or any of the human lambda light chain isoforms. In some cases, the immunoglobulin in the sample is denatured prior to enzymatic cleavage. For example, the immunoglobulin can be denatured by heat, treatment with urea, disulfide reduction, and/or cysteine alkylation.

In some embodiments, the method further involves a treating step to isolate the target immunoglobulin prior to enzymatic cleavage. For example, the treating step can involve one or more of size exclusion chromatography, gel electrophoresis, and/or affinity chromatography.

The immunoglobulin in the sample can be enzymatically cleaved by proteolytic enzyme digestion. Non-limiting examples of proteolytic enzymes include trypsin, pepsin, endoproteinase Lys-C, chymotrypsin, endoproteinase Glu-C, endoproteinase Asp-N, and endoproteinase Arg-C, and any combination thereof.

In some embodiments, the one or more variable peptide fragments are measured by spiking in during the mass spectrometry a known amount of the one or more variable peptides containing a specific label. For example, the specific label can be a heavy isotope label or an amino acid substitution sufficient to create a detectable mass difference. Non-limiting examples of heavy isotope labels include ²H, ¹³C, and ¹⁵N. The amino acid replacements are preferably conservative substitutions, e.g. leucine to valine or aspartic acid to glutamic acid.

Also disclosed herein are methods for quantifying total immunoglobulin in the biological sample by detecting constant domain peptides fragments containing amino acid sequences from a constant domain of the immunoglobulin that are conserved within each class of immunoglobulin. In some embodiments, the method involves determining the ratio of target immunoglobulin (i.e., variable domain peptides) to total immunoglobulin (i.e., constant domain peptides) in the biological sample. This ratio identifies the amount of normal immunoglobulin, which can be used to detect immune paresis.

The mass spectrometry of the disclosed methods preferably involves the use of liquid chromatography coupled to multiple reaction monitoring (LC-MRM). For rapid sample analysis, direct infusion-MRM could also be used. Parallel reaction monitoring and pseudo-MRM could also be used to identify and quantify the peptides using fragment ions observed in tandem mass spectrometry. The mass spectrometry can be conducted on a triple quadrupole mass spectrometer. Ion trap, orbital ion trap, and hybrid quadrupole-time-of-flight mass spectrometers could also be used.

The plasma cell dyscrasia (PCD) can be any plasma cell cancer that results in overproduction of an immunoglobulin. Non-limiting examples of PCDs include multiple myeloma, monoclonal gammopathy of undetermined significance (MGUS), solitary plasmacytoma of bone, extramedullary plasmacytoma, Waldenström's macroglobulinemia (WM), primary amyloidosis, light chain deposition disease and heavy-chain disease. For example, where the PCD is a multiple myeloma, the plasma cells used to sequence the target immunoglobulin can be CD138⁺ cells, e.g., extracted from bone marrow aspirates.

The spectrum of MGUS, solitary plasmacytoma of bone, and asymptomatic and symptomatic multiple myeloma may actually represent a natural progression of the same disease. The disclosed methods may be especially useful to monitor this progression, by precise measurement of the increases in signal/amount of the immunoglobulin secreted by the tumor cells.

The methods may also be used to monitor the efficacy of a treatment regimen on a subject with a PCD, such as multiple myeloma or MGUS, by evaluating the decrease of the signal/amount for the immunoglobulin specific to the disease. This can also be used to detect and eliminate minimal residual disease (MRD) since it can detect antibodies from tumor cells at levels approximately 67 times lower than conventional methods.

In addition, these methods could be used for more sensitive detection of relapse, which would open earlier therapeutic windows and could lead to more effective intervention and better patient outcomes. In some embodiments, the methods involve selecting an alternative therapy if relapse is detected.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1: Box plots Comparing Monoclonal Immunoglobulin Expression in Serum for MM Patients with IgG, IgA, and IgM Diagnoses to Other Patients. Patients with positive diagnosis for specific immunoglobulin types, IgG (A), IgA (B), and IgM (C), are compared with other patients, including both patients not diagnosed with MM and patients diagnosed with MM that express other types of monoclonal immunoglobulins. Data are not included for IgD (n=5) and IgE (n=1), because the separation is clear between those patients and the rest of the population. Current clinical measurements are not able to determine the expression of IgG (or IgA) isoforms, but specific peptides from each sequence can be monitored by LC-MRM to differentiate the isoforms of these heavy chains. Patients with each IgG subtype, IgG1 (D) and IgG3 (E) are compared with all other patients in the study. Data are not included for IgA2 (n=0), IgG2 (n=2), or IgG4 (n=1), because the separation is clear between the patients expressing those isoforms and the rest of the population. In each plot, dashed lines indicate the maximum normal immunoglobulin level.

FIG. 2: Correlation of Immunoglobulin Measurements by Nephelometry and LC-MRM Quantification of Peptides Selected from the Constant Region of Each Immunoglobulin. Data from patients whose MM secrete each immunoglobulin (black diamonds) and from other types of patients (open circles) are plotted for IgG (A), IgA (B), and IgM (C) measurements. Insets show values for LC-MRM quantification for samples that were below the threshold for the nephelometry measurements. LC-MRM could also quantify immunoglobulin expression levels that were not detectable by nephelometry; data are presented for IgG (D), IgA (E), and IgM (F).

FIG. 3: LC-MRM Analysis of Total Light Chain Expression in Serum. Box plots are shown to compare patients expressing kappa light chain in their monoclonal to other patients (A) and those expressing lambda light chain to other patients (B). Average κ:λ ratios determined from triplicate LC-MRM measurements are also shown for each patient (C), with the exception of 5 patients with κ monoclonals that produced detectable, but not quantifiable, amounts of λ light chain. The normal ratio for total expression of light chains in healthy adults (1.3-2.7) is outlined by dotted lines in the inset (C); three patients with low monoclonal immunoglobulin expression had ratios on the opposite side of the normal range from the light chain indicated in their diagnosis.

FIG. 4: LC-MRM and Nephelometry Have Similar Sensitivity for Detection of Treatment Response in an IgE MM Patient. The patient was monitored over time with SPEP (A-C) as well as nephelometry and LC-MRM (D) starting at the time of diagnosis and continuing through the treatment regimen of a clinical trial combining a proteasome inhibitor and an immunomodulator. Both SPEP (circle) and LC-MRM (diamonds) results show IgE elevation at diagnosis (A). During treatment (B and C), the SPEP is negative, but elevated IgE is still detected by nephelometry (squares) and LC-MRM (D, letters A-C indicate quantification from the same serum samples as the SPEP data panels above) are still able to detect elevated IgE. Nephelometry and LC-MRM can observe the decrease in tumor burden after the 5^(th) cycle of treatment, and IgE is not detected (ND) in the patient serum by either method after the 6^(th) cycle of therapy. Tumor burden is reduced by three orders of magnitude, before the immunoglobulin is no longer detected.

FIG. 5: RNA-Seq, Protein Sequence, and LC-MRM Verification of Constant and Variable Region Peptides for H929 MM Cells. RNA-seq and in silico translation produced a protein sequence, which was verified by LC-MRM detection of constant (C1-C3) and variable region (V1-V6) peptides from digests of conditioned media (A). Spiked H929 Igκ could also be detected in control serum (B).

FIG. 6: Detection of Peptides from the Disease-Specific Igκ Light Chain. Three peptides derived from RNA-seq and κ light chain assembly using tumor cells from Patient 1 were observed with LC-MRM in a serum sample with 0.2 g/dl M-protein: VTITCR (SEQ ID NO:23) (FIG. 6A), SLIYAASSLQSGVPSK (SEQ ID NO:24) (FIG. 6C), and ANQDITNSLVWFQQK (SEQ ID NO:25) (FIG. 6D). Data are provided from Patient 2 to illustrate the uniqueness of the three peptides (FIG. 6B, FIG. 6D, and FIG. 6F, respectively).

FIG. 7: Exemplary workflow for personalized detection of multiple myeloma tumor burden. Each immunoglobulin (Ig) has unique sequences in the complementarity defining region (black bars), which will be unique to the tumor (A). Two methods are shown for defining the Ig sequence: RNA sequencing and de novo peptide sequencing. Then assays developed for patients are used for longitudinal monitoring of tumor burden.

DETAILED DESCRIPTION

Liquid chromatography-multiple reaction monitoring mass spectrometry (LC-MRM) using stable isotope dilution has enabled the assessment of protein biomarkers (Barr J R, et al Clin Chem 1996, 42, 1676-82; Barnidge D R, et al Anal Chem 2003, 75, 445-51; Gerber S A, et al Proc Natl Acad Sci USA 2003, 100, 6940-45; Anderson L, et al Mol Cell Proteomics 2006, 5, 573-88; Kuzyk M A, et al Mol Cell Proteomics 2009, 8, 1860-77; Keshishian H, et al Mol Cell Proteomics 2007, 6, 2212-29; Kirsch S, et al J Chromatogr A 2007, 1153, 300-6; Kuhn E, et al Proteomics 2004, 4, 1175-86; Barnidge D R, et al J Proteome Res 2004, 3, 644-52; Yocum A K, et al Proteomics 2010, 10, 3506-14). In addition, collaborative groups have standardized LC-MRM assays at multiple sites (Addona T A, et al Nat Biotechnol 2009, 27, 633-41; Prakash A, et al J Proteome Res 2010, 9, 6678-88). Based on these advances, this technology holds great promise for patient assessment, and LC-MRM is being used in translational research programs (Koomen J M, et al Mol Cell Proteomics 2008, 7, 1780-94). This technology has also been used to measure clinically-relevant protein biomarkers, including troponin I and interleukin-33 (Kuhn E, et al Clin Chem 2009, 55, 1108-17), apolipoproteins (Agger S A, et al Clin Chem 2010, 56, 1804-13), and thyroglobulin (Hoofnagle A N, et al Clin Chem 2008, 54, 1796-804).

Quantification of immunoglobulins can be achieved at two levels. Peptides from the constant regions can be quantified to evaluate levels of total immunoglobulin expression. The comparison of LC-MRM of constant region peptides to immunoglobulin quantification with current clinical techniques provides information about the utility, advantages, and disadvantages of the technique. In addition, development of assays for peptides from the variable region enables a measurement of the disease-specific immunoglobulin, similar in specificity to SPEP detection. Using the strategy of informing proteomics with RNA-sequencing (Evans V C, et al Nat Methods 2012, 9, 1207-11), data are provided for personalized detection of myeloma tumor burden using RNA-sequencing and LC-MRM variable region peptide detection for both an in vitro system (i.e. H929 cells) and patients.

Disclosed is a method for detecting and quantifying the tumor burden in patients with a PCD, such as multiple myeloma. RNA sequencing from tumor cells can be used to define the sequence of the immunoglobulin protein that they secrete. This protein can be measured in blood or urine to assess the patient. The disclosed methods increase sensitivity for determining the tumor burden in patients with a PCD, such as multiple myeloma. These measurements can better define the response to therapy and detect relapse earlier.

In current clinical practice, the presence of monoclonal immunoglobulin is detected or quantified by serum protein electrophoresis (SPEP) and the total amount of the immunoglobulin is quantified by nephelometry. In reaction monitoring mass spectrometry, specific structural fragments are isolated from specific peptide precursors and quantified by the integration of their peak area. Each precursor and fragment pair is termed a transition. Several transitions detected at the same time provide confidence in the quantification of the molecule.

A level of antibody can, for example, be determined by comparing to a reference standard of known values. A person of skill in the art is capable of preparing a reference standard of known values. The reference standard can be prepared at the same time, prior to, or after determination of the level of antibody. For MRM mass spectrometry, these standards are typically stable-labeled peptides but peptides that are structurally analogous to the sequence of interest can also be used if stable-labeled peptides are not available. The signals for the endogenous (biological) peptide are compared to the same set of signals from the standard peptide to enable quantification.

As used herein a control can comprise a known value or reference sample. A known value refers to a value from a diseased sample or a group of diseased samples, which can represent, a sample from a subject diagnosed with cancer or a disease associated with antibody production. Optionally, the reference sample is from a diseased subject of similar size, weight, height and gender, as the subject being tested or a pooled sample from multiple healthy controls.

Optionally, the antibody comprises a heavy chain selected from the group consisting of IgG1-4, IgA1-2, IgM, IgD, and IgE. Optionally, the antibody comprises a light chain selected from a kappa light chain or a lambda light chain.

Constant Region Peptides

Exemplary peptides for LC-MRM quantification of total immunoglobulin or specific isoforms are provided below. These measurements can be paired with the detection of specific sequences from the disease-specific monoclonal immunoglobulin to understand disease burden and assist in detecting relapse if another tumor cell secreting a different immunoglobulin grows out after treatment. All peptides listed below can include possible alkylation of cysteine with iodoacetamide (or comparable reagents) and methionine oxidation. In addition, peptides with missed cleavages could be detected, which would be made of combinations of the sequences below.

IgG1 Peptides from Constant Region Trypsin: (SEQ ID NO: 26) GFYPSDIAVEWESNGQPENNYK, (SEQ ID NO: 27) TPEVTCVVVDVSHEDPEVK, (SEQ ID NO: 28) TTPPVLDSDGSFFLYSK, (SEQ ID NO: 29) VVSVLTVLHQDWLNGK, (SEQ ID NO: 30) FNWYVDGVEVHNAK, (SEQ ID NO: 31) EPQVYTLPPSR, (SEQ ID NO: 32) STSGGTAALGCLVK, (SEQ ID NO: 33) EEQYNSTYR, (SEQ ID NO: 1) GPSVFPLAPSSK, (SEQ ID NO: 34) NQVSLTCLVK, (SEQ ID NO: 35) ALPAPIEK, (SEQ ID NO: 36) DTLMISR, (SEQ ID NO: 37) SLSLSPGK; Lys-C: (SEQ ID NO: 38) GFYPSDIAVEWESNGQPENNYK, (SEQ ID NO: 39) THTCPPCPAPELLGGPSVFLFPPK, (SEQ ID NO: 40) GQPREPQVYTLPPSRDELTK, (SEQ ID NO: 41) TTPPVLDSDGSFFLYSK, (SEQ ID NO: 42) FNWYVDGVEVHNAK, (SEQ ID NO: 43) STSGGTAALGCLVK, (SEQ ID NO: 44) GPSVFPLAPSSK, (SEQ ID NO: 45) NQVSLTCLVK, (SEQ ID NO: 46) ALPAPIEK, (SEQ ID NO: 47) SLSLSPGK; Arg-C: (SEQ ID NO: 48) EPQVYTLPPSR, (SEQ ID NO: 49) EEQYNSTYR; Chymotrypsin: (SEQ ID NO: 50) ISRTPEVTCVVVDVSHEDPEVKF, (SEQ ID NO: 51) VDGVEVHNAKTKPREEQY, (SEQ ID NO: 52) APSSKSTSGGTAAL, (SEQ ID NO: 53) ESNGQPENNY, (SEQ ID NO: 54) TSGVHTFPAVL, (SEQ ID NO: 55) ASTKGPSVFPL, (SEQ ID NO: 56) YPSDIAVEW, (SEQ ID NO: 57) SSVVTVPSSSL, (SEQ ID NO: 58) FPEPVTVSW, (SEQ ID NO: 59) FPPKPKDTL, (SEQ ID NO: 60) TLPPSRDEL, (SEQ ID NO: 61) TVDKSRW, (SEQ ID NO: 62) TKNQVSL, (SEQ ID NO: 63) KTTPPVL; Glu-C (phosphate buffer): (SEQ ID NO: 64) QYNSTYRVVSVLTVLHQD, (SEQ ID NO: 65) LTKNQVSLTCLVKGFYPSD, (SEQ ID NO: 66) KSRWQQGNVFSCSVMHE, (SEQ ID NO: 67) ALHNHYTQKSLSLSPGK, (SEQ ID NO: 68) LLGGPSVFLFPPKPKD, (SEQ ID NO: 69) YKCKVSNKALPAPIE, (SEQ ID NO: 70) GSFFLYSKLTVD, (SEQ ID NO: 71) VHNAKTKPREE, (SEQ ID NO: 72) KTHTCPPCPAPE, (SEQ ID NO: 73) NNYKTTPPVLD, (SEQ ID NO: 74) VKFNWYVD, (SEQ ID NO: 75) TLMISRTPE, (SEQ ID NO: 76) KKVEPKSCD, (SEQ ID NO: 77) WLNGKE; Glu-C (bicarbonate buffer): (SEQ ID NO: 78) LTKNQVSLTCLVKGFYPSDIAVE, (SEQ ID NO: 79) ALHNHYTQKSLSLSPGK, (SEQ ID NO: 80) YKCKVSNKALPAPIE, (SEQ ID NO: 81) VKFNWYVDGVE, (SEQ ID NO: 82) VHNAKTKPREE, (SEQ ID NO: 83) VTCVVVDVSHE, (SEQ ID NO: 84) SNGQPE; Asp-N: (SEQ ID NO: 85) DIAVEWESNGQPENNYKTTPPVL, (SEQ ID NO: 86) DELTKNQVSLTCLVKGFYPS, (SEQ ID NO: 87) DTLMISRTPEVTCVVV, (SEQ ID NO: 88) DGSFFLYSKLTV, (SEQ ID NO: 89) DPEVKFNWYV, (SEQ ID NO: 90) DKKVEPKSC; IgG2 Peptides from Constant Region Trypsin: (SEQ ID NO: 91) GFYPSDISVEWESNGQPENNYK, (SEQ ID NO: 92) TTPPMLDSDGSFFLYSK, (SEQ ID NO: 93) VVSVLTVVHQDWLNGK, (SEQ ID NO: 94) STSESTAALGCLVK, (SEQ ID NO: 95) EPQVYTLPPSR, (SEQ ID NO: 96) GPSVFPLAPCSR, (SEQ ID NO: 97) EEQFNSTFR, (SEQ ID NO: 98) NQVSLTCLVK, (SEQ ID NO: 99) DTLMISR, (SEQ ID NO: 2) GLPAPIEK, (SEQ ID NO: 100) SLSLSPGK; Lys-C: (SEQ ID NO: 101) GPSVFPLAPCSRSTSESTAALGCLVK, (SEQ ID NO: 102) GFYPSDISVEWESNGQPENNYK, (SEQ ID NO: 103) CCVECPPCPAPPVAGPSVFLFPPK, (SEQ ID NO: 104) GQPREPQVYTLPPSREEMTK, (SEQ ID NO: 105) TTPPMLDSDGSFFLYSK, (SEQ ID NO: 106) NQVSLTCLVK, (SEQ ID NO: 107) GLPAPIEK, (SEQ ID NO: 108) SLSLSPGK; Arg-C: (SEQ ID NO: 109) ASTKGPSVFPLAPCSR, (SEQ ID NO: 110) EPQVYTLPPSR, (SEQ ID NO: 111) EEQFNSTFR; Chymotrypsin: (SEQ ID NO: 112) ISRTPEVTCVVVDVSHEDPEVQF, (SEQ ID NO: 113) VDGVEVHNAKTKPREEQF, (SEQ ID NO: 114) APCSRSTSESTAAL, (SEQ ID NO: 115) ESNGQPENNY, (SEQ ID NO: 116) TSGVHTFPAVL, (SEQ ID NO: 117) SSVVTVPSSNF, (SEQ ID NO: 118) ASTKGPSVFPL, (SEQ ID NO: 119) YPSDISVEW, (SEQ ID NO: 120) FPEPVTVSW, (SEQ ID NO: 121) TLPPSREEM, (SEQ ID NO: 122) FPPKPKDTL, (SEQ ID NO: 123) TVDKSRW, (SEQ ID NO: 124) TVVHQDW, (SEQ ID NO: 125) TKNQVSL; Glu-C (phosphate buffer): (SEQ ID NO: 126) CPPCPAPPVAGPSVFLFPPK PKD, (SEQ ID NO: 127) MTKNQVSLTCLVKGFYPSD, (SEQ ID NO: 128) QFNSTFRVVSVLTVVHQD, (SEQ ID NO: 129) KSRWQQGNVFSCSVMHE, (SEQ ID NO: 130) ASTKGPSVFPLAPCSRSTSE, (SEQ ID NO: 131) ALHNHYTQKSLSLSPGK, (SEQ ID NO: 132) YKCKVSNKGLPAPIE, (SEQ ID NO: 133) GSFFLYSKLTVD, (SEQ ID NO: 134) VHNAKTKPREE, (SEQ ID NO: 135) NNYKTTPPMLD, (SEQ ID NO: 136) STAALGCLVKD, (SEQ ID NO: 137) VQFNWYVD, (SEQ ID NO: 138) TLMISRTPE, (SEQ ID NO: 139) HKPSNTKVD, (SEQ ID NO: 140) WLNGKE, (SEQ ID NO: 141) RKCCVE, (SEQ ID NO: 142) VTCVVVD; Glu-C (bicarbonate buffer): (SEQ ID NO: 143) MTKNQVSLTCLVKGFYPSDISVE, (SEQ ID NO: 144) ASTKGPSVFPLAPCSRSTSE, (SEQ ID NO: 145) ALHNHYTQKSLSLSPGK, (SEQ ID NO: 146) YKCKVSNKGLPAPIE, (SEQ ID NO: 147) VQFNWYVDGVE, (SEQ ID NO: 148) VHNAKTKPREE, (SEQ ID NO: 149) VTCVVVDVSHE, (SEQ ID NO: 150) RKCCVE; Asp-N: (SEQ ID NO: 151) DISVEWESNGQPENNYKTTPPML, (SEQ ID NO: 152) DTLMISRTPEVTCVVV, (SEQ ID NO: 153) DGSFFLYSKLTV, (SEQ ID NO: 154) DPEVQFNWYV, (SEQ ID NO: 155) DHKPSNTKV; IgG3 Peptides from Constant Region Trypsin: (SEQ ID NO: 156) TPEVTCVVVDVSHEDPEVQFK, (SEQ ID NO: 157) WQQGNIFSCSVMHEALHNR, (SEQ ID NO: 158) CPAPELLGGPSVFLFPPKPK, (SEQ ID NO: 159) VVSVLTVLHQDWLNGK, (SEQ ID NO: 3) WYVDGVEVHNAK, (SEQ ID NO: 160) TPLGDTTHTCPR, (SEQ ID NO: 161) EPQVYTLPPSR, (SEQ ID NO: 162) STSGGTAALGCLVK, (SEQ ID NO: 163) GPSVFPLAPCSR, (SEQ ID NO: 164) EEQYNSTFR, (SEQ ID NO: 165) NQVSLTCLVK, (SEQ ID NO: 166) SCDTPPPCPR, (SEQ ID NO: 167) ALPAPIEK, (SEQ ID NO: 168) DTLMISR, (SEQ ID NO: 169) SLSLSPGK; Lys-C: (SEQ ID NO: 170) GPSVFPLAPCSRSTSGGTAALGCLVK, (SEQ ID NO: 171) GQPREPQVYTLPPSREEMTK, (SEQ ID NO: 172) TPLGDTTHTCPRCPEPK, (SEQ ID NO: 173) SCDTPPPCPRCPEPK, (SEQ ID NO: 174) WYVDGVEVHNAK, (SEQ ID NO: 175) NQVSLTCLVK, (SEQ ID NO: 176) ALPAPIEK, (SEQ ID NO: 177) SLSLSPGK; Arg-C: (SEQ ID NO: 178) WQQGNIFSCSVMHEALHNR, (SEQ ID NO: 179) VELKTPLGDTTHTCPR, (SEQ ID NO: 180) CPEPKSCDTPPPCPR, (SEQ ID NO: 181) ASTKGPSVFPLAPCSR, (SEQ ID NO: 182) FTQKSLSLSPGK, (SEQ ID NO: 183) EPQVYTLPPSR, (SEQ ID NO: 184) EEQYNSTFR; Chymotrypsin: (SEQ ID NO: 185) ISRTPEVTCVVVDVSHEDPEVQF, (SEQ ID NO: 186) TCNVNHKPSNTKVDKRVEL, (SEQ ID NO: 187) VDGVEVHNAKTKPREEQY, (SEQ ID NO: 188) APCSRSTSGGTAAL, (SEQ ID NO: 189) TSGVHTFPAVL, (SEQ ID NO: 190) ESSGQPENNY, (SEQ ID NO: 191) ASTKGPSVFPL, (SEQ ID NO: 192) YPSDIAVEW, (SEQ ID NO: 193) SSVVTVPSSSL, (SEQ ID NO: 194) FPEPVTVSW, (SEQ ID NO: 195) TLPPSREEM, (SEQ ID NO: 196) FPPKPKDTL, (SEQ ID NO: 197) TVDKSRW, (SEQ ID NO: 198) TKNQVSL; Glu-C (phosphate buffer): (SEQ ID NO: 199) MTKNQVSLTCLVKGFYPSD, (SEQ ID NO: 200) QYNSTFRVVSVLTVLHQD, (SEQ ID NO: 201) KSRWQQGNIFSCSVMHE, (SEQ ID NO: 202) ALHNRFTQKSLSLSPGK, (SEQ ID NO: 203) LLGGPSVFLFPPKPKD, (SEQ ID NO: 204) TTHTCPRCPEPKSCD, (SEQ ID NO: 205) YKCKVSNKALPAPIE, (SEQ ID NO: 206) TPPPCPRCPEPKSCD, (SEQ ID NO: 207) GSFFLYSKLTVD, (SEQ ID NO: 208) VHNAKTKPREE, (SEQ ID NO: 209) NNYNTTPPMLD, (SEQ ID NO: 210) TPPPCPRCPAPE, (SEQ ID NO: 211) VQFKWYVD, (SEQ ID NO: 212) TLMISRTPE, (SEQ ID NO: 213) WLNGKE, (SEQ ID NO: 214) LKTPLGD, (SEQ ID NO: 215) VTCVVVD; Glu-C (bicarbonate buffer): (SEQ ID NO: 216) MTKNQVSLTCLVKGFYPSDIAVE, (SEQ ID NO: 217) ALHNRFTQKSLSLSPGK, (SEQ ID NO: 218) YKCKVSNKALPAPIE, (SEQ ID NO: 219) VQFKWYVDGVE, (SEQ ID NO: 220) VHNAKTKPREE, (SEQ ID NO: 221) VTCVVVDVSHE; Asp-N: (SEQ ID NO: 222) DIAVEWESSGQPENNYNTTPPML, (SEQ ID NO: 223) DTLMISRTPEVTCVVV, (SEQ ID NO: 224) DTTHTCPRCPEPKSC, (SEQ ID NO: 225) DTPPPCPRCPEPKSC, (SEQ ID NO: 226) DGSFFLYSKLTV, (SEQ ID NO: 227) DPEVQFKWYV, (SEQ ID NO: 228) DKRVELKTPLG; IgG4 Peptides from Constant Region Trypsin: (SEQ ID NO: 229) GFYPSDIAVEWESNGQPENNYK, (SEQ ID NO: 4) TTPPVLDSDGSFFLYSR, (SEQ ID NO: 230) EPQVYTLPPSQEEMTK, (SEQ ID NO: 231) VVSVLTVLHQDWLNGK, (SEQ ID NO: 232) TYTCNVDHKPSNTK, (SEQ ID NO: 233) STSESTAALGCLVK, (SEQ ID NO: 234) GPSVFPLAPCSR, (SEQ ID NO: 235) EEQFNSTYR, (SEQ ID NO: 236) NQVSLTCLVK, (SEQ ID NO: 237) DTLMISR, (SEQ ID NO: 238) GLPSSIEK, (SEQ ID NO: 239) SLSLSLGK; Lys-C: (SEQ ID NO: 240) GPSVFPLAPCSRSTSESTAALGCLVK, (SEQ ID NO: 241) GFYPSDIAVEWESNGQPENNYK, (SEQ ID NO: 242) TTPPVLDSDGSFFLYSRLTVDK, (SEQ ID NO: 243) GQPREPQVYTLPPSQEEMTK, (SEQ ID NO: 244) NQVSLTCLVK, (SEQ ID NO: 245) TYTCNVDHK, (SEQ ID NO: 246) GLPSSIEK, (SEQ ID NO: 247) SLSLSLGK; Arg-C: (SEQ ID NO: 248) ASTKGPSVFPLAPCSR, (SEQ ID NO: 249) EEQFNSTYR, (SEQ ID NO: 250) LTVDKSR; Chymotrypsin: (SEQ ID NO: 251) ISRTPEVTCVVVDVSQEDPEVQF, (SEQ ID NO: 252) TCNVDHKPSNTKVDKRVESKY, (SEQ ID NO: 253) VDGVEVHNAKTKPREEQF, (SEQ ID NO: 254) APCSRSTSESTAAL, (SEQ ID NO: 255) GPPCPSCPAPEF, (SEQ ID NO: 256) ESNGQPENNY, (SEQ ID NO: 257) TSGVHTFPAVL, (SEQ ID NO: 258) ASTKGPSVFPL, (SEQ ID NO: 259) YPSDIAVEW, (SEQ ID NO: 260) SSVVTVPSSSL, (SEQ ID NO: 261) FPEPVTVSW, (SEQ ID NO: 262) FPPKPKDTL, (SEQ ID NO: 263) TLPPSQEEM, (SEQ ID NO: 264) TVDKSRW, (SEQ ID NO: 265) TKNQVSL, (SEQ ID NO: 266) KTTPPVL; Glu-C (phosphate buffer): (SEQ ID NO: 267) MTKNQVSLTCLVKGFYPSD, (SEQ ID NO: 268) QFNSTYRVVSVLTVLHQD, (SEQ ID NO: 269) ASTKGPSVFPLAPCSRSTSE, (SEQ ID NO: 270) ALHNHYTQKSLSLSLGK, (SEQ ID NO: 271) FLGGPSVFLFPPKPKD, (SEQ ID NO: 272) YKCKVSNKGLPSSIE, (SEQ ID NO: 273) SKYGPPCPSCPAPE, (SEQ ID NO: 274) GSFFLYSRLTVD, (SEQ ID NO: 275) VHNAKTKPREE, (SEQ ID NO: 276) NNYKTTPPVLD, (SEQ ID NO: 277) GNVFSCSVMHE, (SEQ ID NO: 278) STAALGCLVKD, (SEQ ID NO: 279) VQFNWYVD, (SEQ ID NO: 280) TLMISRTPE, (SEQ ID NO: 281) HKPSNTKVD, (SEQ ID NO: 282) KSRWQE, (SEQ ID NO: 283) WLNGKE, (SEQ ID NO: 284) VTCVVVD; Glu-C (bicarbonate buffer): (SEQ ID NO: 285) MTKNQVSLTCLVKGFYPSDIAVE, (SEQ ID NO: 286) ASTKGPSVFPLAPCSRSTSE, (SEQ ID NO: 287) ALHNHYTQKSLSLSLGK, (SEQ ID NO: 288) YKCKVSNKGLPSSIE, (SEQ ID NO: 289) SKYGPPCPSCPAPE, (SEQ ID NO: 290) VQFNWYVDGVE, (SEQ ID NO: 291) VHNAKTKPREE, (SEQ ID NO: 292) GNVFSCSVMHE, (SEQ ID NO: 293) VTCVVVDVSQE; Asp-N: (SEQ ID NO: 294) DIAVEWESNGQPENNYKTTPPVL, (SEQ ID NO: 295) DTLMISRTPEVTCVVV, (SEQ ID NO: 296) DGSFFLYSRLTV, (SEQ ID NO: 297) DPEVQFNWYV, (SEQ ID NO: 298) DHKPSNTKV; IgA1 Peptides from Constant Region Trypsin: (SEQ ID NO: 299) DLCGCYSVSSVLPGCAEPWNHGK, (SEQ ID NO: 300) LAGKPTHVNVSVVMAEVDGTCY, (SEQ ID NO: 301) GDTFSCMVGHEALPLAFTQK, (SEQ ID NO: 302) QEPSQGTTTFAVTSILR, (SEQ ID NO: 303) DASGVTFTWTPSSGK, (SEQ ID NO: 304) TFTCTAAYPESK, (SEQ ID NO: 305) WLQGSQELPR, (SEQ ID NO: 306) SAVQGPPER, (SEQ ID NO: 5) TPLTATLSK, (SEQ ID NO: 307) YLTWASR, (SEQ ID NO: 308) VAAEDWK, (SEQ ID NO: 309) SVTCHVK, (SEQ ID NO: 310) ASPTSPK; Lys-C: (SEQ ID NO: 311) GDTFSCMVGHEALPLAFTQK, (SEQ ID NO: 312) DVLVRWLQGSQELPREK, (SEQ ID NO: 313) PTHVNVSVVMAEVDGTCY, (SEQ ID NO: 314) TFTCTAAYPESK, (SEQ ID NO: 315) TPLTATLSK, (SEQ ID NO: 316) TIDRLAGK, (SEQ ID NO: 317) SVTCHVK; Arg-C: (SEQ ID NO: 318) DASGVTFTWTPSSGKSAVQGPPER, (SEQ ID NO: 319) LAGKPTHVNVSVVMAEVDGTCY, (SEQ ID NO: 320) QEPSQGTTTFAVTSILR, (SEQ ID NO: 321) WLQGSQELPR, (SEQ ID NO: 322) EKYLTWASR, (SEQ ID NO: 323) GFSPKDVLVR; Chymotrypsin: (SEQ ID NO: 324) SESGQGVTARNFPPSQDASGDL, (SEQ ID NO: 325) TPSSGKSAVQGPPERDL, (SEQ ID NO: 326) CSTQPDGNVVIACL, (SEQ ID NO: 327) ASRQEPSQGTTTF, (SEQ ID NO: 328) TCTAAYPESKTPL, (SEQ ID NO: 329) AGKPTHVNVSVVM, (SEQ ID NO: 330) QGSQELPREKY, (SEQ ID NO: 331) SVSSVLPGCAEPW, (SEQ ID NO: 332) AGKSVTCHVKHY, (SEQ ID NO: 333) ASPTSPKVFPL, (SEQ ID NO: 334) TQKTIDRL, (SEQ ID NO: 335) LPPPSEEL, (SEQ ID NO: 336) AEVDGTCY, (SEQ ID NO: 337) RDASGVTF, (SEQ ID NO: 338) TLPATQCL, (SEQ ID NO: 339) RVAAEDW, (SEQ ID NO: 340) VGHEALPL, (SEQ ID NO: 341) RPEVHL, (SEQ ID NO: 342) SKSGNTF, (SEQ ID NO: 343) FPQEPL; Glu-C (phosphate buffer): (SEQ ID NO: 344) GNVVIACLVQGFFPQEPLSVTWSE, (SEQ ID NO: 345) ASGVTFTWTPSSGKSAVQGPPE, (SEQ ID NO: 346) SKTPLTATLSKSGNTFRPE, (SEQ ID NO: 347) ASPTSPKVFPLSLCSTQPD, (SEQ ID NO: 348) RLAGKPTHVNVSVVMAE, (SEQ ID NO: 349) LVTLTCLARGFSPKD, (SEQ ID NO: 350) SGQGVTARNFPPSQD, (SEQ ID NO: 351) ALPLAFTQKTID, (SEQ ID NO: 352) VLVRWLQGSQE, (SEQ ID NO: 353) ANLTCTLTGLRD, (SEQ ID NO: 354) VHLLPPPSEE, (SEQ ID NO: 903) TFSCMVGHE;; Glu-C (bicarbonate buffer): (SEQ ID NO: 355) SKTPLTATLSKSGNTFRPE, (SEQ ID NO: 356) DWKKGDTFSCMVGHE, (SEQ ID NO: 357) VHLLPPPSEE, (SEQ ID NO: 358) DLLLGSE; Asp-N: (SEQ ID NO: 359) DASGVTFTWTPSSGKSAVQGPPER, (SEQ ID NO: 360) DTFSCMVGHEALPLAFTQKTI, (SEQ ID NO: 361) DRLAGKPTHVNVSVVMAEV, (SEQ ID NO: 362) DLLLGSEANLTCTLTGLR, (SEQ ID NO: 363) ASPTSPKVFPLSLCSTQP; IgA2 Peptides from Constant Region Trypsin: (SEQ ID NO: 364) MAGKPTHVNVSVVMAEVDGTCY, (SEQ ID NO: 365) GDTFSCMVGHEALPLAFTQK, (SEQ ID NO: 366) QEPSQGTTTFAVTSILR, (SEQ ID NO: 6) DASGATFTWTPSSGK, (SEQ ID NO: 367) WLQGSQELPR, (SEQ ID NO: 368) TPLTANITK, (SEQ ID NO: 369) SAVQGPPER, (SEQ ID NO: 370) YLTWASR, (SEQ ID NO: 371) VAAEDWK, (SEQ ID NO: 372) SVTCHVK; Lys-C: (SEQ ID NO: 373) GDTFSCMVGHEALPLAFTQK, (SEQ ID NO: 374) DVLVRWLQGSQELPREK, (SEQ ID NO: 375) PTHVNVSVVMAEVDGTCY, (SEQ ID NO: 376) TPLTANITK, (SEQ ID NO: 377) TIDRMAGK, (SEQ ID NO: 378) SVTCHVK; Arg-C: (SEQ ID NO: 379) DASGATFTWTPSSGKSAVQGPPER, (SEQ ID NO: 380) MAGKPTHVNVSVVMAEVDGTCY, (SEQ ID NO: 381) QEPSQGTTTFAVTSILR, (SEQ ID NO: 382) WLQGSQELPR, (SEQ ID NO: 383) EKYLTWASR, (SEQ ID NO: 384) GFSPKDVLVR, Chymotrypsin: (SEQ ID NO: 385) TNPSQDVTVPCPVPPPPPCCHPRL, (SEQ ID NO: 386) SESGQNVTARNFPPSQDASGDL, (SEQ ID NO: 387) TLPATQCPDGKSVTCHVKHY, (SEQ ID NO: 388) TPSSGKSAVQGPPERDL, (SEQ ID NO: 389) DSTPQDGNVVVACL, (SEQ ID NO: 390) ASRQEPSQGTTTF, (SEQ ID NO: 391) AGKPTHVNVSVVM, (SEQ ID NO: 392) QGSQELPREKY, (SEQ ID NO: 393) SVSSVLPGCAQPW, (SEQ ID NO: 394) TANITKSGNTF, (SEQ ID NO: 395) TQKTIDRM, (SEQ ID NO: 396) TCTAAHPEL, (SEQ ID NO: 397) LPPPSEEL, (SEQ ID NO: 398) AEVDGTCY, (SEQ ID NO: 399) RVAAEDW, (SEQ ID NO: 400) VGHEALPL, (SEQ ID NO: 401) RDASGATF, (SEQ ID NO: 402) RPEVHL, (SEQ ID NO: 403) FPQEPL; Glu-C (phosphate buffer): (SEQ ID NO: 404) LCGCYSVSSVLPGCAQPWNHGE, (SEQ ID NO: 405) ASGATFTWTPSSGKSAVQGPPE, (SEQ ID NO: 406) LKTPLTANITKSGNTFRPE, (SEQ ID NO: 407) GKSVTCHVKHYTNPSQD, (SEQ ID NO: 408) LYTTSSQLTLPATQCPD, (SEQ ID NO: 409) RMAGKPTHVNVSVVMAE, (SEQ ID NO: 410) LVTLTCLARGFSPKD, (SEQ ID NO: 411) SGQNVTARNFPPSQD, (SEQ ID NO: 412) ALPLAFTQKTID, (SEQ ID NO: 413) VLVRWLQGSQE, (SEQ ID NO: 414) ANLTCTLTGLRD, (SEQ ID NO: 415) VHLLPPPSEE, (SEQ ID NO: 416) TFTCTAAHPE, (SEQ ID NO: 417) TFSCMVGHE; Glu-C (bicarbonate buffer): (SEQ ID NO: 418) RDLCGCYSVSSVLPGCAQPWNHGE, (SEQ ID NO: 419) LKTPLTANITKSGNTFRPE, (SEQ ID NO: 420) DWKKGDTFSCMVGHE, (SEQ ID NO: 421) VHLLPPPSEE, (SEQ ID NO: 422) TFTCTAAHPE, (SEQ ID NO: 423) DLLLGSE; Asp-N: (SEQ ID NO: 424) DASGATFTWTPSSGKSAVQG PPER, (SEQ ID NO: 425) DTFSCMVGHEALPLAFTQKT I, (SEQ ID NO: 426) DRMAGKPTHVNVSVVMAEV, (SEQ ID NO: 427) DGKSVTCHVKHYTNPSQ, (SEQ ID NO: 428) DLLLGSEANLTCTLTGLR, (SEQ ID NO: 429) DLYTTSSQLTLPATQCP; IgIVI Peptides from Constant Region Trypsin: (SEQ ID NO: 430) STGKPTLYNVSLVMSDTAGTCY, (SEQ ID NO: 431) LTCLVTDLTTYDSVTISWTR, (SEQ ID NO: 432) GLTFQQNASSMCVPDQDTAIR, (SEQ ID NO: 433) GVALHRPDVYLLPPAR, (SEQ ID NO: 434) FTCTVTHTDLPSPLK, (SEQ ID NO: 435) VFAIPPSFASIFLTK, (SEQ ID NO: 436) QVGSGVTTDQVQAEAK, (SEQ ID NO: 437) YVTSAPMPEPQAPGR, (SEQ ID NO: 438) ESDWLGQSMFTCR, (SEQ ID NO: 439) DVMQGTDEHVVCK, (SEQ ID NO: 440) NVPLPVIAELPPK, (SEQ ID NO: 441) YAATSQVLLPSK, (SEQ ID NO: 442) LICQATGFSPR, (SEQ ID NO: 443) QIQVSWLR, (SEQ ID NO: 444) NNSDISSTR, (SEQ ID NO: 8) DGFFGNPR, (SEQ ID NO: 445) VSVFVPPR, (SEQ ID NO: 446) VQHPNGNK, (SEQ ID NO: 447) ESGPTTYK, (SEQ ID NO: 448) VTSTLTIK, (SEQ ID NO: 449) GQPLSPEK, (SEQ ID NO: 450) QTISRPK, (SEQ ID NO: 451) GFPSVLR, (SEQ ID NO: 452) EQLNLR, (SEQ ID NO: 453) QNGEAVK; Lys-C: (SEQ ID NO: 454) LICQATGFSPRQIQVSWLREGK, (SEQ ID NO: 455) NNSDISSTRGFPSVLRGGK, (SEQ ID NO: 456) PTLYNVSLVMSDTAGTCY, (SEQ ID NO: 457) VSVFVPPRDGFFGNPRK, (SEQ ID NO: 458) QVGSGVTTDQVQAEAK, (SEQ ID NO: 459) DVMQGTDEHVVCK, (SEQ ID NO: 460) NVPLPVIAELPPK, (SEQ ID NO: 461) YAATSQVLLPSK, (SEQ ID NO: 462) VQHPNGNK, (SEQ ID NO: 463) ESGPTTYK, (SEQ ID NO: 464) VTSTLTIK, (SEQ ID NO: 465) QTISRPK; Arg-C: (SEQ ID NO: 466) GQPLSPEKYVTSAPMPEPQAPGR, (SEQ ID NO: 467) GLTFQQNASSMCVPDQDTAIR, (SEQ ID NO: 468) KSKLICQATGFSPR, (SEQ ID NO: 469) QIQVSWLR, (SEQ ID NO: 470) DGFFGNPR, (SEQ ID NO: 471) GFPSVLR, (SEQ ID NO: 472) EQLNLR; Chymotrypsin: (SEQ ID NO: 473) TRQNGEAVKTHTNISESHPNATF, (SEQ ID NO: 474) VSCENSPSDTSSVAVGCL, (SEQ ID NO: 475) KNNSDISSTRGFPSVL, (SEQ ID NO: 476) VTSAPMPEPQAPGRY, (SEQ ID NO: 477) TCTVTHTDLPSPL, (SEQ ID NO: 478) SAVGEASICEDDW, (SEQ ID NO: 479) CVPDQDTAIRVF, (SEQ ID NO: 480) KQTISRPKGVAL, (SEQ ID NO: 481) SPRQIQVSW, (SEQ ID NO: 482) TCRVDHRGL, (SEQ ID NO: 483) RESATITCL, (SEQ ID NO: 484) LPPAREQL, (SEQ ID NO: 485) GNPRKSKL, (SEQ ID NO: 486) TVSEEEW, (SEQ ID NO: 487) TIKESDW, (SEQ ID NO: 488) SDTAGTCY, (SEQ ID NO: 489) DSVTISW, (SEQ ID NO: 490) LPSKDVM, (SEQ ID NO: 491) VPPRDGF, (SEQ ID NO: 492) HRPDVY, (SEQ ID NO: 493) QQNASSM, (SEQ ID NO: 494) LPDSITL, (SEQ ID NO: 495) ICQATGF, (SEQ ID NO: 496) NSGERF; Glu-C (phosphate buffer): (SEQ ID NO: 497) LPSPLKQTISRPKGVALHRPD, (SEQ ID NO: 498) HRGLTFQQNASSMCVPD, (SEQ ID NO: 499) KSTGKPTLYNVSLVMSD, (SEQ ID NO: 500) VFVQWMQRGQPLSPE, (SEQ ID NO: 501) SGPTTYKVTSTLTIKE, (SEQ ID NO: 502) HVVCKVQHPNGNKE, (SEQ ID NO: 503) SITLSWKYKNNSD, (SEQ ID NO: 504) SATITCLVTGFSPAD, (SEQ ID NO: 505) LPPKVSVFVPPRD, (SEQ ID NO: 506) WLGQSMFTCRVD, (SEQ ID NO: 507) SVTISWTRQNGE, (SEQ ID NO: 508) SHPNATFSAVGE, (SEQ ID NO: 509) RFTCTVTHTD, (SEQ ID NO: 510) TSSVAVGCLAQD, (SEQ ID NO: 511) AVKTHTNISE, (SEQ ID NO: 512) KNVPLPVIAE, (SEQ ID NO: 513) VYLLPPARE, (SEQ ID NO: 514) GKQVGSGVTTD, (SEQ ID NO: 515) TYTCVAHE, (SEQ ID NO: 516) ALPNRVTE, (SEQ ID NO: 517) VMQGTDE, (SEQ ID NO: 518) QLNLRE; Glu-C (bicarbonate buffer): (SEQ ID NO: 519) SGPTTYKVTSTLTIKE, (SEQ ID NO: 520) GKQVGSGVTTDQVQAE, (SEQ ID NO: 521) HVVCKVQHPNGNKE, (SEQ ID NO: 522) GSASAPTLFPLVSCE, (SEQ ID NO: 523) SHPNATFSAVGE, (SEQ ID NO: 524) AVKTHTNISE, (SEQ ID NO: 525) KNVPLPVIAE, (SEQ ID NO: 526) TYTCVAHE, (SEQ ID NO: 527) ALPNRVTE, (SEQ ID NO: 528) DDWNSGE, (SEQ ID NO: 529) QLNLRE; Asp-N: (SEQ ID NO: 530) DLPSPLKQTISRPKGVALHR P, (SEQ ID NO: 531) DHRGLTFQQNASSMCVP, (SEQ ID NO: 532) DKSTGKPTLYNVSLVMS, (SEQ ID NO: 533) DWNSGERFTCTVTHT, (SEQ ID NO: 534) DSITLSWKYKNNS, (SEQ ID NO: 535) DWLGQSMFTCRV, (SEQ ID NO: 536) DTSSVAVGCLAQ, (SEQ ID NO: 537) DTAGTCY; IgD Peptides from Constant Region Trypsin: (SEQ ID NO: 538) SLWNAGTSVTCTLNHPSLPPQR, (SEQ ID NO: 539) VPAPPSPQPATYTCVVSHEDSR, (SEQ ID NO: 540) DSYYMTSSQLSTPLQQWR, (SEQ ID NO: 541) AQASSVPTAQPQAEGSLAK, (SEQ ID NO: 542) SLEVSYVTDHGPMK, (SEQ ID NO: 543) ATFTCFVVGSDLK, (SEQ ID NO: 544) VPTGGVEEGLLER, (SEQ ID NO: 545) APDVFPIISGCR, (SEQ ID NO: 546) DAHLTWEVAGK, (SEQ ID NO: 547) HSNGSQSQHSR, (SEQ ID NO: 548) CVVQHTASK, (SEQ ID NO: 11) EPAAQAPVK, (SEQ ID NO: 549) TFPEIQR, (SEQ ID NO: 550) ATTAPATTR, (SEQ ID NO: 551) EEQEER, (SEQ ID NO: 552) TLLNASR, (SEQ ID NO: 553) WPESPK; Lys-C: (SEQ ID NO: 554) AQASSVPTAQPQAEGSLAK, (SEQ ID NO: 555) ATTAPATTRNTGRGGEEK, (SEQ ID NO: 556) APDVFPIISGCRHPK, (SEQ ID NO: 557) ATFTCFVVGSDLK, (SEQ ID NO: 558) EIFRWPESPK, (SEQ ID NO: 559) DAHLTWEVAGK, (SEQ ID NO: 560) EEQEERETK, (SEQ ID NO: 561) CVVQHTASK; Arg-C: (SEQ ID NO: 562) QGEYKCVVQHTASKSKKEIFR, (SEQ ID NO: 563) SLWNAGTSVTCTLNHPSLPPQR, (SEQ ID NO: 564) VPAPPSPQPATYTCVVSHED SR, (SEQ ID NO: 565) DSYYMTSSQLSTPLQQWR, (SEQ ID NO: 566) GGEEKKKEKEKEEQEER, (SEQ ID NO: 567) SLEVSYVTDHGPMK, (SEQ ID NO: 568) HSNGSQSQHSR, (SEQ ID NO: 569) TFPEIQR, (SEQ ID NO: 570) TLLNASR; Chymotrypsin: (SEQ ID NO: 571) RWPESPKAQASSVPTAQPQAEGSL, (SEQ ID NO: 572) GTQSQPQRTFPEIQRRDSY, (SEQ ID NO: 573) KCVVQHTASKSKKEIF, (SEQ ID NO: 574) ERHSNGSQSQHSRL, (SEQ ID NO: 575) EVAGKVPTGGVEEGL, (SEQ ID NO: 576) APARPPPQPGSTTF, (SEQ ID NO: 577) RVPAPPSPQPATY, (SEQ ID NO: 578) TCVVSHEDSRTL, (SEQ ID NO: 579) EDQREVNTSGF, (SEQ ID NO: 580) REPAAQAPVKL, (SEQ ID NO: 581) NHPSLPPQRL, (SEQ ID NO: 582) ASSDPPEAASW, (SEQ ID NO: 583) HPTSVTVTW, (SEQ ID NO: 584) NAGTSVTCTL, (SEQ ID NO: 585) VTDHGPM, (SEQ ID NO: 586) TPAVQDL, (SEQ ID NO: 587) RDKATF; Glu-C (phosphate buffer): (SEQ ID NO: 588) SYYMTSSQLSTPLQQWRQGE, (SEQ ID NO: 589) GSLAKATTAPATTRNTGRGGEE, (SEQ ID NO: 590) CPSHTQPLGVYLLTPAVQD, (SEQ ID NO: 591) YKCVVQHTASKSKKE, (SEQ ID NO: 592) VSGFSPPNILLMWLE, (SEQ ID NO: 593) SPKAQASSVPTAQPQAE, (SEQ ID NO: 594) VFPIISGCRHPKD, (SEQ ID NO: 595) SRTLLNASRSLE, (SEQ ID NO: 596) KATFTCFVVGSD, (SEQ ID NO: 597) VAGKVPTGGVEE, (SEQ ID NO: 598) AASWLLCE, (SEQ ID NO: 599) IFRWPE, (SEQ ID NO: 600) AHLTWE; Glu-C (bicarbonate buffer): (SEQ ID NO: 601) GSLAKATTAPATTRNTGRGGEE, (SEQ ID NO: 602) YKCVVQHTASKSKKE, (SEQ ID NO: 603) VSGFSPPNILLMWLE, (SEQ ID NO: 604) SPKAQASSVPTAQPQAE, (SEQ ID NO: 605) DSRTLLNASRSLE, (SEQ ID NO: 606) VSYVTDHGPMK, (SEQ ID NO: 607) VAGKVPTGGVEE, (SEQ ID NO: 608) AASWLLCE; Asp-N: (SEQ ID NO: 609) DSRTLLNASRSLEVSYVT, (SEQ ID NO: 610) DVFPIISGCRHPK, (SEQ ID NO: 611) DKATFTCFVVGS; IgE Peptides from Constant Region Trypsin: (SEQ ID NO: 612) TYTCQVTYQGHTFEDSTK, (SEQ ID NO: 613) GVSAYLSRPSPFDLFIR, (SEQ ID NO: 614) AAPEVYAFATPEWPGSR, (SEQ ID NO: 615) VAHTPSSTDWVDNK, (SEQ ID NO: 616) SPTITCLVVDLAPSK, (SEQ ID NO: 617) NGTLTVTSTLPVGTR, (SEQ ID NO: 618) AVHEAASPSQTVQR, (SEQ ID NO: 619) DWIEGETYQCR, (SEQ ID NO: 620) ASGKPVNHSTR, (SEQ ID NO: 621) GTVNLTWSR, (SEQ ID NO: 12) GSGFFVFSR, (SEQ ID NO: 622) VTHPHLPR, (SEQ ID NO: 623) DFTPPTVK, (SEQ ID NO: 624) HSTTQPR, (SEQ ID NO: 625) HWLSDR, (SEQ ID NO: 626) TFSVCSR, (SEQ ID NO: 627) AEWEQK, (SEQ ID NO: 628) QMFTCR, (SEQ ID NO: 629) DEFICR, (SEQ ID NO: 630) AVSVNPGK, (SEQ ID NO: 631) CADSNPR; Lys-C: (SEQ ID NO: 632) TSGPRAAPEVYAFATPEWPGSRDK, (SEQ ID NO: 633) GSGFFVFSRLEVTRAEWEQK, (SEQ ID NO: 634) QMFTCRVAHTPSSTDWVDNK, (SEQ ID NO: 635) TFSVCSRDFTPPTVK, (SEQ ID NO: 636) SPTITCLVVDLAPSK, (SEQ ID NO: 637) GTVNLTWSRASGK, (SEQ ID NO: 638) PVNHSTRK  Arg-C: (SEQ ID NO: 639) VAHTPSSTDWVDNKTFSVCSR, (SEQ ID NO: 640) GVSAYLSRPSPFDLFIR, (SEQ ID NO: 641) AAPEVYAFATPEWPGSR, (SEQ ID NO: 642) AEWEQKDEFICR, (SEQ ID NO: 643) NGTLTVTSTLPVGTR, (SEQ ID NO: 644) AVHEAASPSQTVQR, (SEQ ID NO: 645) DWIEGETYQCR, (SEQ ID NO: 646) KTKGSGFFVFSR, (SEQ ID NO: 647) ASGKPVNHSTR, (SEQ ID NO: 648) VTHPHLPR, (SEQ ID NO: 649) STTKTSGPR, (SEQ ID NO: 650) HSTTQPR, (SEQ ID NO: 651) KEEKQR, (SEQ ID NO: 652) AVSVNPGK  Chymotrypsin: (SEQ ID NO: 653) ICRAVHEAASPSQTVQRAVSVNPGK, (SEQ ID NO: 654) SRASGKPVNHSTRKEEKQRNGTL, (SEQ ID NO: 655) EDSTKKCADSNPRGVSAY, (SEQ ID NO: 656) RSTTKTSGPRAAPEVY, (SEQ ID NO: 657) TRCCKNIPSNATSVTL, (SEQ ID NO: 658) QSSCDGGGHFPPTIQL, (SEQ ID NO: 659) ATPEWPGSRDKRTL, (SEQ ID NO: 660) QCRVTHPHLPRAL, (SEQ ID NO: 661) TCRVAHTPSSTDW, (SEQ ID NO: 662) TVTSTLPVGTRDW, (SEQ ID NO: 663) IRKSPTITCL, (SEQ ID NO: 664) STASTTQEGEL, (SEQ ID NO: 665) MPEDISVQW, (SEQ ID NO: 666) TPGTINITW, (SEQ ID NO: 667) EVTRAEW, (SEQ ID NO: 668) APSKGTVNL, (SEQ ID NO: 669) TPPTVKIL, (SEQ ID NO: 670) SVCSRDF, (SEQ ID NO: 671) EQKDEF, (SEQ ID NO: 672) ASTQSEL, (SEQ ID NO: 673) VDNKTF; Glu-C (phosphate buffer): (SEQ ID NO: 674) ARHSTTQPRKTKGSGFFVFSRLE, (SEQ ID NO: 675) KQRNGTLTVTSTLPVGTRD, (SEQ ID NO: 676) SNPRGVSAYLSRPSPFD, (SEQ ID NO: 677) RTYTCQVTYQGHTFE, (SEQ ID NO: 678) AASPSQTVQRAVSVNPGK, (SEQ ID NO: 679) LFIRKSPTITCLVVD, (SEQ ID NO: 680) KRTLACLIQNFMPE, (SEQ ID NO: 681) FTPPTVKILQSSCD, (SEQ ID NO: 682) LTLSQKHWLSD, (SEQ ID NO: 683) NKTFSVCSRD, (SEQ ID NO: 684) ISVQWLHNE, (SEQ ID NO: 685) FICRAVHE, (SEQ ID NO: 686) LSTASTTQE, (SEQ ID NO: 687) VYAFATPE, (SEQ ID NO: 688) STKKCAD, (SEQ ID NO: 689) LASTQSE, (SEQ ID NO: 690) WPGSRD; Glu-C (bicarbonate buffer): (SEQ ID NO: 691) KQRNGTLTVTSTLPVGTRDWIE, (SEQ ID NO: 692) WPGSRDKRTLACLIQNFMPE, (SEQ ID NO: 693) AASPSQTVQRAVSVNPGK, (SEQ ID NO: 694) DGQVMDVDLSTASTTQE, (SEQ ID NO: 695) DISVQWLHNE, (SEQ ID NO: 696) FICRAVHE, (SEQ ID NO: 697) VYAFATPE, (SEQ ID NO: 698) LASTQSE; Asp-N: (SEQ ID NO: 699) DRTYTCQVTYQGHTFE, (SEQ ID NO: 700) DSNPRGVSAYLSRPSPF, (SEQ ID NO: 701) DKRTLACLIQNFMPE, (SEQ ID NO: 702) DLFIRKSPTITCLVV, (SEQ ID NO: 703) DISVQWLHNEVQLP, (SEQ ID NO: 704) DFTPPTVKILQSSC, (SEQ ID NO: 705) DNKTFSVCSR, (SEQ ID NO: 706) DSTKKCA; Igκ Peptides from Constant Region Trypsin: (SEQ ID NO: 707) VDNALQSGNSQESVTEQDSK, (SEQ ID NO: 9) TVAAPSVFIFPPSDEQLK, (SEQ ID NO: 708) VYACEVTHQGLSSPVTK, (SEQ ID NO: 709) SGTASVVCLLNNFYPR, (SEQ ID NO: 710) DSTYSLSSTLTLSK; Lys-C: (SEQ ID NO: 711) VDNALQSGNSQESVTEQDSK, (SEQ ID NO: 712) SGTASVVCLLNNFYPREAK, (SEQ ID NO: 713) TVAAPSVFIFPPSDEQLK, (SEQ ID NO: 714) VYACEVTHQGLSSPVTK, (SEQ ID NO: 715) DSTYSLSSTLTLSK, (SEQ ID NO: 716) SFNRGEC; Chymotrypsin: (SEQ ID NO: 717) QSGNSQESVTEQDSKDSTY, (SEQ ID NO: 718) YPREAKVQW, (SEQ ID NO: 719) IFPPSDEQL, (SEQ ID NO: 720) KSGTASVVCL, (SEQ ID NO: 721) ACEVTHQGL, (SEQ ID NO: 722) SSPVTKSF, (SEQ ID NO: 723) EKHKVY, (SEQ ID NO: 724) TVAAPSVF; Glu-C (phosphate buffer): (SEQ ID NO: 725) QLKSGTASVVCLLNNFYPRE, (SEQ ID NO: 726) VTHQGLSSPVTKSFNRGE, (SEQ ID NO: 727) TVAAPSVFIFPPSDE, (SEQ ID NO: 728) STYSLSSTLTLSKAD, (SEQ ID NO: 729) NALQSGNSQE, (SEQ ID NO: 730) KHKVYACE, (SEQ ID NO: 731) AKVQWKVD; Glu-C (bicarbonate buffer): (SEQ ID NO: 732) QDSKDSTYSLSSTLTLSKADYE, (SEQ ID NO: 733) QLKSGTASVVCLLNNFYPRE, (SEQ ID NO: 734) AKVQWKVDNALQSGNSQE, (SEQ ID NO: 735) VTHQGLSSPVTKSFNRGE, (SEQ ID NO: 736) TVAAPSVFIFPPSDE, (SEQ ID NO: 737) KHKVYACE; Asp-N: (SEQ ID NO: 738) NALQSGNSQESVTEQ, (SEQ ID NO: 739) DSTYSLSSTLTLSKA, (SEQ ID NO: 740) TVAAPSVFIFPPS; Igλ1 Peptides from Constant Region Trypsin: (SEQ ID NO: 741) ATLVCLISDFYPGAVTVAWK, (SEQ ID NO: 742) ANPTVTLFPPSSEELQANK, (SEQ ID NO: 743) YAASSYLSLTPEQWK, (SEQ ID NO: 744) SYSCQVTHEGSTVEK, (SEQ ID NO: 745) AGVETTKPSK, (SEQ ID NO: 746) TVAPTECS; Lys-C: (SEQ ID NO: 747) ATLVCLISDFYPGAVTVAWK, (SEQ ID NO: 748) ANPTVTLFPPSSEELQANK, (SEQ ID NO: 749) SHRSYSCQVTHEGSTVEK, (SEQ ID NO: 750) YAASSYLSLTPEQWK, (SEQ ID NO: 751) TVAPTECS, (SEQ ID NO: 752) AGVETTK, (SEQ ID NO: 753) ADGSPVK; Arg-C: (SEQ ID NO: 754) SYSCQVTHEGSTVEKTVAPTECS; Chymotrypsin: (SEQ ID NO: 755) KADGSPVKAGVETTKPSKQSNNKY, (SEQ ID NO: 756) SCQVTHEGSTVEKTVAPTECS, (SEQ ID NO: 757) GQPKANPTVTL, (SEQ ID NO: 758) YPGAVTVAW, (SEQ ID NO: 759) FPPSSEEL, (SEQ ID NO: 760) KSHRSY, (SEQ ID NO: 761) QANKATL; Glu-C (phosphate buffer): (SEQ ID NO: 762) TTKPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 763) GQPKANPTVTLFPPSSEE, (SEQ ID NO: 764) QWKSHRSYSCQVTHE, (SEQ ID NO: 765) LQANKATLVCLISD, (SEQ ID NO: 766) FYPGAVTVAWKAD, (SEQ ID NO: 904) GSPVKAGVE, (SEQ ID NO: 767) KTVAPTE; Glu-C (bicarbonate buffer): (SEQ ID NO: 768) TTKPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 769) GQPKANPTVTLFPPSSEE, (SEQ ID NO: 770) QWKSHRSYSCQVTHE, (SEQ ID NO: 771) KTVAPTE; Asp-N: (SEQ ID NO: 772) DFYPGAVTVAWKA; Igλ2 Peptides from Constant Region Trypsin: (SEQ ID NO: 773) ATLVCLISDFYPGAVTVAWK, (SEQ ID NO: 774) AAPSVTLFPPSSEELQANK, (SEQ ID NO: 775) YAASSYLSLTPEQWK, (SEQ ID NO: 776) SYSCQVTHEGSTVEK, (SEQ ID NO: 10) AGVETTTPSK, (SEQ ID NO: 777) TVAPTECS, (SEQ ID NO: 778) ADSSPVK; Lys-C: (SEQ ID NO: 779) ATLVCLISDFYPGAVTVAWK, (SEQ ID NO: 780) SHRSYSCQVTHEGSTVEK, (SEQ ID NO: 781) AAPSVTLFPPSSEELQANK, (SEQ ID NO: 782) YAASSYLSLTPEQWK, (SEQ ID NO: 783) AGVETTTPSK, (SEQ ID NO: 784) TVAPTECS, (SEQ ID NO: 785) ADSSPVK; Arg-C: (SEQ ID NO: 786) SYSCQVTHEGSTVEKTVAPTECS; Chymotrypsin: (SEQ ID NO: 787) KADSSPVKAGVETTTPSKQSNNKY, (SEQ ID NO: 788) SCQVTHEGSTVEKTVAPTECS, (SEQ ID NO: 789) GQPKAAPSVTL, (SEQ ID NO: 790) YPGAVTVAW, (SEQ ID NO: 791) FPPSSEEL, (SEQ ID NO: 792) KSHRSY, (SEQ ID NO: 793) QANKATL; Glu-C (phosphate buffer): (SEQ ID NO: 794) TTTPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 795) QWKSHRSYSCQVTHE, (SEQ ID NO: 796) GQPKAAPSVTLFPPSSEE, (SEQ ID NO: 797) LQANKATLVCLISD, (SEQ ID NO: 798) FYPGAVTVAWKAD, (SEQ ID NO: 799) SSPVKAGVE, (SEQ ID NO: 800) KTVAPTE; Glu-C (bicarbonate buffer): (SEQ ID NO: 801) TTTPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 802) QWKSHRSYSCQVTHE, (SEQ ID NO: 803) GQPKAAPSVTLFPPSSEE, (SEQ ID NO: 804) KTVAPTE; Asp-N: (SEQ ID NO: 805) DFYPGAVTVAWKA; Igλ3 Peptides from Constant Region Trypsin: (SEQ ID NO: 806) ATLVCLISDFYPGAVTVAWK, (SEQ ID NO: 807) AAPSVTLFPPSSEELQANK, (SEQ ID NO: 808) YAASSYLSLTPEQWK, (SEQ ID NO: 809) SYSCQVTHEGSTVEK, (SEQ ID NO: 810) AGVETTTPSK, (SEQ ID NO: 811) TVAPTECS; Lys-C: (SEQ ID NO: 812) ATLVCLISDFYPGAVTVAWK, (SEQ ID NO: 813) AAPSVTLFPPSSEELQANK, (SEQ ID NO: 814) YAASSYLSLTPEQWK, (SEQ ID NO: 815) SYSCQVTHEGSTVEK, (SEQ ID NO: 816) AGVETTTPSK, (SEQ ID NO: 817) TVAPTECS, (SEQ ID NO: 818) ADSSPAK; Chymotrypsin: (SEQ ID NO: 819) KADSSPAKAGVETTTPSKQSNNKY, (SEQ ID NO: 820) SCQVTHEGSTVEKTVAPTECS, (SEQ ID NO: 821) GQPKAAPSVTL, (SEQ ID NO: 822) YPGAVTVAW, (SEQ ID NO: 823) FPPSSEEL, (SEQ ID NO: 824) KSHKSY, (SEQ ID NO: 825) QANKATL; Glu-C (phosphate buffer): (SEQ ID NO: 826) TTTPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 827) QWKSHKSYSCQVTHE, (SEQ ID NO: 828) GQPKAAPSVTLFPPSSEE, (SEQ ID NO: 829) LQANKATLVCLISD, (SEQ ID NO: 830) FYPGAVTVAWKAD, (SEQ ID NO: 831) SSPAKAGVE, (SEQ ID NO: 832) KTVAPTE; Glu-C (bicarbonate buffer): (SEQ ID NO: 833) TTTPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 834) QWKSHKSYSCQVTHE, (SEQ ID NO: 835) GQPKAAPSVTLFPPSSEE, (SEQ ID NO: 836) KTVAPTE; Asp-N: (SEQ ID NO: 837) DFYPGAVTVAWKA; Igλ6 Peptides from Constant Region Trypsin: (SEQ ID NO: 838) AAPSVTLFPPSSEELQANK, (SEQ ID NO: 839) YAASSYLSLTPEQWK, (SEQ ID NO: 840) ATLVCLISDFYPGAVK, (SEQ ID NO: 841) ADGSPVNTGVETTTPSK, (SEQ ID NO: 842) SYSCQVTHEGSTVEK, (SEQ ID NO: 843) TVAPAECS; Lys-C: (SEQ ID NO: 844) SHRSYSCQVTHEGSTVEK, (SEQ ID NO: 845) AAPSVTLFPPSSEELQANK, (SEQ ID NO: 846) YAASSYLSLTPEQWK, (SEQ ID NO: 847) ATLVCLISDFYPGAVK, (SEQ ID NO: 848) ADGSPVNTGVETTTPSK, (SEQ ID NO: 849) TVAPAECS; Arg-C: (SEQ ID NO: 850) SYSCQVTHEGSTVEKTVAPAECS; Chymotrypsin: (SEQ ID NO: 851) KADGSPVNTGVETTTPSKQSNNKY, (SEQ ID NO: 852) SCQVTHEGSTVEKTVAPAECS, (SEQ ID NO: 853) GQPKAAPSVTL, (SEQ ID NO: 854) YPGAVKVAW, (SEQ ID NO: 855) FPPSSEEL, (SEQ ID NO: 856) KSHRSY, (SEQ ID NO: 857) QANKATL; Glu-C (phosphate buffer): (SEQ ID NO: 858) TTTPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 859) QWKSHRSYSCQVTHE, (SEQ ID NO: 860) GQPKAAPSVTLFPPSSEE, (SEQ ID NO: 861) LQANKATLVCLISD, (SEQ ID NO: 862) FYPGAVKVAWKAD, (SEQ ID NO: 863) GSPVNTGVE, (SEQ ID NO: 864) KTVAPAE; Glu-C (bicarbonate buffer): (SEQ ID NO: 865) TTTPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 866) QWKSHRSYSCQVTHE, (SEQ ID NO: 867) GQPKAAPSVTLFPPSSEE, (SEQ ID NO: 868) KTVAPAE; Asp-N: (SEQ ID NO: 869) DFYPGAVKVAWKA; Igλ7 Peptides from Constant Region Trypsin: (SEQ ID NO: 870) ATLVCLVSDFYPGAVTVAWK, (SEQ ID NO: 871) AAPSVTLFPPSSEELQANK, (SEQ ID NO: 872) YAASSYLSLTPEQWK, (SEQ ID NO: 873) VTHEGSTVEK, (SEQ ID NO: 874) VGVETTKPSK, (SEQ ID NO: 875) TVAPAECS; Lys-C: (SEQ ID NO: 876) ATLVCLVSDFYPGAVTVAWK, (SEQ ID NO: 877) SHRSYSCRVTHEGSTVEK, (SEQ ID NO: 878) AAPSVTLFPPSSEELQANK, (SEQ ID NO: 879) YAASSYLSLTPEQWK, (SEQ ID NO: 880) TVAPAECS, (SEQ ID NO: 881) VGVETTK, (SEQ ID NO: 882) ADGSPVK; Arg-C: (SEQ ID NO: 883) VTHEGSTVEKTVAPAECS; Chymotrypsin: (SEQ ID NO: 884) KADGSPVKVGVETTKPSKQSNNKY, (SEQ ID NO: 885) SCRVTHEGSTVEKTVAPAECS, (SEQ ID NO: 886) GQPKAAPSVTL, (SEQ ID NO: 887) YPGAVTVAW, (SEQ ID NO: 888) FPPSSEEL, (SEQ ID NO: 889) KSHRSY, (SEQ ID NO: 890) QANKATL; Glu-C (phosphate buffer): (SEQ ID NO: 891) TTKPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 892) QWKSHRSYSCRVTHE, (SEQ ID NO: 893) GQPKAAPSVTLFPPSSEE, (SEQ ID NO: 894) LQANKATLVCLVSD, (SEQ ID NO: 895) FYPGAVTVAWKAD, (SEQ ID NO: 896) GSPVKVGVE, (SEQ ID NO: 897) KTVAPAE; Glu-C (bicarbonate buffer): (SEQ ID NO: 898) TTKPSKQSNNKYAASSYLSLTPE, (SEQ ID NO: 899) QWKSHRSYSCRVTHE, (SEQ ID NO: 900) GQPKAAPSVTLFPPSSEE, (SEQ ID NO: 901) KTVAPAE; and Asp-N: (SEQ ID NO: 902) DFYPGAVTVAWKA.

Definitions

The term “subject” refers to any individual who is the target of administration or treatment. The subject can be a vertebrate, for example, a mammal Thus, the subject can be a human or veterinary patient. The term “patient” refers to a subject under the treatment of a clinician, e.g., physician.

The term “biological sample” refers to any sample from a subject that may contain immunoglobulin secreted from plasma cells. Non-limiting examples include blood, urine, plasma, and serum.

The terms “peptide,” “protein,” and “polypeptide” are used interchangeably to refer to a natural or synthetic molecule comprising two or more amino acids linked by the carboxyl group of one amino acid to the alpha amino group of another.

As used herein, the term “amino acid sequence” refers to a list of abbreviations, letters, characters or words representing amino acid residues. The amino acid abbreviations used herein are conventional one letter codes for the amino acids and are expressed as follows: A, alanine; B, asparagine or aspartic acid; C, cysteine; D aspartic acid; E, glutamate, glutamic acid; F, phenylalanine; G, glycine; H histidine; I isoleucine; K, lysine; L, leucine; M, methionine; N, asparagine; P, proline; Q, glutamine; R, arginine; S, serine; T, threonine; V, valine; W, tryptophan; Y, tyrosine; Z, glutamine or glutamic acid.

A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

EXAMPLES Example 1: Quantification of Peptides from Immunoglobulin Constant and Variable Regions by Liquid Chromatography-Multiple Reaction Monitoring Mass Spectrometry for Assessment of Multiple Myeloma Patients

Materials and Methods

Chemicals and reagents were acquired from Sigma-Aldrich (Milwaukee, Wis.); HPLC solvents were purchased from Burdick and Jackson (Honeywell, Muskegon, Mich.). Standard peptides were synthesized, HPLC-purified, characterized with MALDI MS, QqQ MS, and amino acid analysis, as previously described (Remily-Wood E R, et al Proteomics Clin Appl 2011, 5, 383-96).

Sample Collection and Summary of Patient Data

De-identified serum was collected from patients in accordance with protocols approved by the University of South Florida Institutional Review Board. Blood was collected in serum separator tubes (BD, Franklin Lakes, N.J.), clotted for 30 minutes, spun down at 3,600 rpm for 10 minutes (5702, Eppendorf), and refrigerated until analysis (t<3 weeks). Samples (n=83) were collected. The study population contained 46 males and 37 females between ages 34 and 87 (median age 63) with diagnoses including MM (45), smoldering MM (3), light chain only MM (1), non-secretory MM (1) MGUS (6), plasmacytoma (5), plasma cell leukemia (2), Waldenstrom's macroglobinemia (8), Non-Hodgkin's Lymphoma (6), other leukemias or lymphomas (4), amyloidosis (2), and prostate cancer (1). Samples were selected to represent all types of PCDs with varying levels of immunoglobulin expression and age-matched patients with other diseases. Of these patients, 71 had elevated levels of immunoglobulin expression detected by SPEP compared to reference values for healthy controls. Twelve patients had immunoglobulin expression levels comparable to healthy controls and were not detectable by SPEP (SPEP−).

Bone marrow aspirates were collected from 2 patients (not included in the cohort used for the constant region analysis). MM tumor cells were obtained by Ficoll and CD138⁺ plasma cell selection (Miltenyi, Auburn, Calif.). An aliquot of 0.5 million cells was used for RNA-sequencing.

Clinical Measurements

SPEP was performed using capillary zone electrophoresis (Capillarys, Sebia). Immunoglobulin concentrations were calculated using measurements of total serum protein (Fusion 5.1FS Chemistry Analyzer, Ortho Clinical Diagnostics, NJ). Immunotyping was performed using monospecific antisera for IgG, IgA, and IgM heavy chains as well as κ and λ light chains (Capillarys, Sebia) Immunofixation electrophoresis (SPIFE 3000, Helena Laboratories) was used to confirm serum immunotyping results or to test for IgD and IgE. Nephelometry of the immunoglobulins was performed (Vitros 5.1 FS Chemistry System, Ortho-Clinical Diagnostics) to determine the concentration of IgA, IgG, and IgM using goat antisera as the primary active reagents.

LC-MRM Quantification of Proteins in Serum

Peptide targets were selected from LC-MS/MS data (see FIG. 51). Serum proteins were denatured with 8M urea, reduced with tris(2-carboxyethyl) phosphine, and alkylated with iodoacetamide prior to a ten-fold dilution in aqueous 30 mM ammonium bicarbonate and in-solution tryptic digestion (Promega, Madison, Wis.). Internal standards were spiked into each sample (Table 1) (Berth M, et al Clin Chem 1999, 45, 309-10; French MAH, et al Clin Exp Immunol 1984, 56, 473-5; Haraldsson A, et al Ann Clin Biochem 1991, 28, 461-66; Chen K, et al Nephrology 2005, 10, 594-596; Buckley R, et al J Clin Invest 1975, 55, 157-65; Hunder G, et al Arthritis Rheum 1974, 17, 955-63). The equivalent of 0.5 nanoliters of tryptically digested serum was injected for each LC-MRM analysis.

TABLE 1 Endogenous Peptides and Labeled Standards used for LC-MRM Quantification of Immunoglobulins. Average Expression & Median Median Reference Intra- Inter- Range Assay Assay Protein (mg/ml) Peptide IS Transitions CV (%) CV (%) Outliers IgG1 5.91 GPSVFPLAPSSK 10.2 y₈-y₁₀ 7.5 7.2 3 3.19-10.2 (SEQ ID NO: 1) IgG2 3.04 GLPAPIEK 6.63 y₄-y₆ 6.0 5.9 2 1.23-6.63 (SEQ ID NO: 2) IgG3 0.61 WYVDGVEVHNAK 1.94 y₆, y₈, y₉ 16 18.3 12 0.16-1.94 (SEQ ID NO: 3) IgG4 0.24 TTPPVLDSDGSFFLYSR NS y₈, y₁₀, y₁₂ — — — 0.03-1.33 (SEQ ID NO: 4) IgA1 1.88 TPLTATLSK NS y₅-y₇ — — — 1.36-2.5  (SEQ ID NO: 5) IgA2 0.54 DASGATFTWTPSSGK* 0.6  y₇-y₁₀ 21 16 5 0.28-0.61 (SEQ ID NO: 6) IgA1-2 2.42 WLQGSQELPR 3.1 y₆-y₈ 6.8 9.6 2 1.64-3.11 (SEQ ID NO: 7) IgM 0.70 DGFFGNPR 2.3 y₄-y₆ 11 7.6 1 0.4-2.3 (SEQ ID NO: 8) κ LC 2.31 TVAAPSVFIFPPSDEQLK* 3.0 y₈, y₉, y₁₁ 7.3 6.6 6 1.55-3.08 (SEQ ID NO: 9) λ LC 1.54 AGVETTTPSK 2.24 y₅-y₇ 19 9.0 16 0.83-2.24 (SEQ ID NO: 10) IgD 0.0139 EPAAQAPVK 0.50 y₅-y₇ 0.52 — 0 0.001-0.024 (SEQ ID NO: 11) IgE 0.0001 GSGFFVFSR* 0.50 y₅-y₇ 6.7 — 0     0-0.002 (SEQ ID NO: 12) Albumin 35 LVNEVTEFAK* 3.5 y₅, y₇, y₈ 5.0 6.3 0 30-40 (SEQ ID NO: 13) Peptides representative for individual proteins and groups of isoforms are quantified. Standard peptides were synthesized with either isotope-labeled amino acids or with a structural analog created by single conservative amino acid replacement (as noted by *) that differs only by a methylene group in the side chain of the underlined residue. The limit of detection based on internal standards is also shown along with other monitored peptides that do not have quantitative assays developed. Eleven additional peptides are monitored to improve confidence in quantification by evaluation of consistency, but SIS peptides have not been synthesized. Reference ranges provided by ARUP Laboratories.

LC-MRM was performed using a nanoLC interfaced with a triple quadrupole mass spectrometer (EasyNanoLC and TSQ Quantum Ultra or Vantage, Thermo, San Jose, Calif.), as previously described (see supplement for additional details) (Remily-Wood E R, et al Proteomics Clin Appl 2011, 5, 383-96). Briefly, peptides were desalted on a reversed phase pre-column prior to reversed phase chromatography using 10 minute gradients (C18 Pepmap100, Thermo, San Jose, Calif.). Peptide precursors were selected with 0.4 Q1 resolution; fragment ions were then selected with 0.7 Q3 resolution. Scan width was 0.002, and transitions were acquired for 5-20 milliseconds. If the peptides were not optimized by manual infusion, collision energy values were calculated using Equation 1 based on the mass-to-charge ratio (m/z) of the doubly protonated peptide precursor (MacLean B, et al Bioinformatics, 2010, 26, 966-8; Zhang G, et al J Proteome Res 2011, 10, 305-19). CE=(0.034*m/z)+3.314 V  Equation 1:

Batches of ten samples were analyzed on the instrument with a reverse calibration curve of the following three standards: a common serum standard was spiked with stable isotope-labeled standard peptides at the average normal abundance, maximum normal abundance, and maximum normal abundance plus 1 mg/ml. Samples were analyzed one through ten, followed by standard samples, and then this batch was repeated for triplicate measurements.

Data Analysis

Peak areas (PA) were calculated using MRMer implemented in GenePattern. Raw data files were converted into mz×ml; LC-MRM peaks were extracted and visualized for transition evaluation. Resulting data were assessed for quality control and compared between patient groups using Post-MRMer. After data review, protein concentrations (in mg/ml) were calculated using the PA ratio of the endogenous peptide to its corresponding standard. The resulting data were evaluated using existing reference ranges for protein-based measurements and compared with nephelometry measurements. Intra-assay CV values were determined using triplicate LC-MRM analysis; inter-assay CV values were calculated from ten LC-MRM analyses of different preparations of the same serum samples (n=3). Median values are reported. Batch-to-batch variation was also examined.

Statistical Analyses

To evaluate assay robustness, the data set was filtered for outliers, when CV>0.5 and at least one value calculated to be above the previously defined range of healthy controls. Samples below the defined normal maximum value were not examined for outliers because the low protein expression level often contributed to increased CV values. In the cases with high CV values, an individual measurement was discarded when its distance from the median was twice (or greater) the distance of the other data point from the median. Out of 249 data points for each peptide, zero to fifteen outliers were removed (see Table 1). Batch effects were also evaluated using the reverse calibration curves and visual inspection of the entire dataset for all 83 patient specimens. From the remaining sample points, the mean, median, and standard deviation were calculated and a two-sided Wilcoxon rank-sum test was used to determine if a statistical difference existed between the expression of each protein in patients diagnosed with each specific type of PCD (as determined by clinical diagnoses for the different immunoglobulins or LC-MRM analysis for specific isoforms of IgA and IgG) and all other patient samples. The Holm-Bonferroni method was used to adjust for multiple hypotheses testing with type I error (α), which was set to 0.05.

RNA Sequencing and LC-MRM Detection of Variable Region Peptides

H929 multiple myeloma cells and two patient specimens (all n=0.5×10⁶ cells) were selected for a proof-of-concept experiment in immunoglobulin variable region sequencing and detection of variable region peptides. mRNA sequencing (RNA-seq) was performed from 100 ng of total RNA using the Encore Complete Library System (NuGEN, San Carlos, Calif.). Strand-specific cDNA generated from this kit was used to prepare a barcoded library appropriate for multiplexed massively parallel sequencing. Paired-end 100 base reads (n˜2×10⁷) were generated using the HiScan SQ sequencer (Illumina, San Diego, Calif.). Demultiplexing and data quality evaluation were performed using CASAVA 1.8.2 (Illumina) RNA-seq reads were aligned to the human hs37d5 reference genome and the Gencode v14 gene model using Tophat2. The expressed transcripts were assembled and evaluated using the de novo assembly software, Trinity. Contiguous sequences are aligned back to the human genome with BLAST, and best hits are manually examined. NCBI ORF identifies potential protein constructs. After generating the protein sequence for the immunoglobulin secreted by the tumor cells, LC-MRM was used to screen for the detection of tryptic peptides from the Igκ constant and variable regions in H929 conditioned culture media, as described above. For patient specimens, both samples were analyzed for LC-MRM detection of variable region peptides from Patient 1 to examine their detection in low levels of disease and against a control background.

Results and Discussion

LC-MRM Quantification of Heavy Chains Using Constant Region Peptides

Triplicate LC-MRM analysis was performed on 83 patient samples. For most standards, spike-in concentrations equivalent to the maximum value for expression in healthy controls to enabled rapid patient evaluation (higher endogenous peptide signal indicates disease burden). Spiked amounts of the internal standards for albumin and those common to multiple IgG isoforms were decreased due to their high abundance in serum. Due to the low abundance of IgD and IgE in healthy controls, their internal standards were spiked at 0.5 mg/ml (or 0.05 g/dl), which is well below the typical limit for starting treatment after disease relapse and half the limit of detection for SPEP. With the exception of peptides monitoring IgA isoforms, median CV values were below 20%.

Comparison of SPEP/IFE results to LC-MRM is useful for verification that the new technique is able to accurately discern involved immunoglobulins for PCD patients. As expected, LC-MRM detection of increased expression of immunoglobulins matched the clinical diagnoses made by serial SPEP/IFE measurements in all cases when the involved immunoglobulin abundance exceeded the reference range for healthy controls. Samples were taken from 19 IgG patients (average SPEP 14.9 mg/ml), 20 IgA patients (average SPEP 14.0 mg/ml), and 17 patients with elevated IgM (average SPEP 10.8 mg/ml). LC-MRM was able to identify increased expression in 18/19 patients with IgG disease. For SPEP+ patients with IgA disease, 18/20 could be detected by LC-MRM of the peptide, WLQGSQELPR (SEQ ID NO:7). The relative quantification of the second peptide from IgA1 detected elevated expression in one of these patients, but the total IgA expression was in the normal range for the other patient. When SPEP detects low levels the monoclonal immunoglobulin but the total immunoglobulin expression level was still in the reference range for healthy controls, both LC-MRM and nephelometry were unable to detect the disease. Longitudinal monitoring of these IgG and IgA patients may still indicate the presence of disease and increases in tumor burden. All 17 SPEP+ IgM cases could be detected. All IgD (n=5) and IgE (n=1) patients were also correctly identified. Seven patients diagnosed with free light chain disease expressed no elevated concentrations of any heavy chain immunoglobulin. LC-MRM measurements of immunoglobulins were in the normal range for all SPEP− samples. Samples from two patients with biclonal MM diagnoses made by SPEP/IFE were analyzed with LC-MRM (one IgG/IgM and one IgA/IgG). Both immunoglobulin chains were detected above the normal range for the IgA/IgG biclonal patient, but only the elevated IgM expression was detected in the IgM/IgG biclonal patient.

The LC-MRM heavy chain measurements correlated well to the values determined by nephelometry, the current clinical standard for quantification. Comparison of IgG measurements using the two methods is shown in FIG. 1A. LC-MRM IgG data was compiled by summing the IgG1, IgG2, and IgG3 values. Because the IgG4 could not be quantified absolutely (due to poor synthesis of the SIS peptide), that value is excluded, and LC-MRM measurements should be slightly less than those from nephelometry (i.e. slope <1). This calculation may also limit the correlation (R²=0.82). Correlation was poorer in patients with high IgG expression levels, perhaps due to LC-MRM saturation from nanoLC column loading limits. Removal of the samples with saturated IgG detection increased the correlation between LC-MRM and nephelometry (R²=0.98). IgA and IgM values were also highly correlated (FIG. 1B and FIG. 1C). In addition, both LC-MRM and nephelometry measurements were compared to SPEP data. As expected, LC-MRM and nephelometry correlate better with each other than with SPEP, due to the fact that they both measure the total immunoglobulin rather than the disease-specific M-protein.

LC-MRM has better sensitivity than nephelometry, but has slightly poorer precision. LC-MRM was able to quantify immunoglobulin concentrations in patients when nephelometry reported that the values were below the stated limits of quantification: 2.71 mg/ml IgG, 0.41 mg/ml IgA, and 0.26 mg/ml IgM. Data are shown for IgG (n=11) in FIG. 1D, IgA (n=29) in FIG. 1E, and IgM (n=34) in FIG. 1F. This improvement in sensitivity may enable better evaluation of immune paresis, reduction of the population of other plasma cells due to the clonal expansion of the tumor cells, which could have a bearing on patient prognosis. Intra-assay and inter-assay CV values are approximately 5% and 10% for nephelometry (Alexander Jr R L Clin Chem 1980, 26, 314-7; Guiguet M, et al J Clin Chem Biochem 1983, 21, 217-21); LC-MRM intra-assay CV values are competitive, but inter-assay CV values are ˜2-fold higher due to the additional processing steps (Table 1).

LC-MRM of constant region peptides also enables the quantification of individual immunoglobulin heavy chain isoforms, which builds on existing clinical methods. This additional information could enable more sensitive detection of disease for patients with MM tumors that secrete lower abundance isoforms (e.g. IgG4). In order to assess the value of this additional level of detail provided by LC-MRM, the expression levels of each immunoglobulin were compared between the patients expressing each monoclonal immunoglobulin and those with other types of PCDs. Box plots are used for visualization (FIG. 2), and statistical results are included in Table 2. In FIG. 2A, the IgG patients are compared to other samples (as described above). IgA patients were differentiated using a peptide representing total IgA, WLQGSQELPR (SEQ ID NO:7) (FIG. 2B). IgM levels were detected using the peptide, DGFFGNPR (SEQ ID NO:8) (FIG. 2C). Box plots are not shown for IgD or IgE, because of the low sample size of those patients and limited detection of those endogenous peptides. As expected, statistical significance improves as the normal range of protein expression decreases; in other words, quantification of total immunoglobulin levels is more effective at detecting disease when the background levels of that immunoglobulin are lower. Therefore, LC-MRM detection of isoforms can further separate IgG patients (defined by serial SPEP/IFE measurements) into IgG1 (n=11), IgG2 (n=2), IgG3 (n=4), and IgG4 (n=1) based on the elevation of isoform-specific peptides. Two examples are shown in box plots in FIG. 2; statistical results are included in Table 2 to indicate the increased separation of the groups and subsequently better detection of elevated immunoglobulin levels for IgG isoforms with lower total expression. Patients identified by LC-MRM with IgG1 disease (n=11) had significantly higher IgG1 expression levels than other patients (FIG. 2D). Patients with IgG3 disease (n=4) had significantly higher levels of that isoform than other patients (FIG. 2E). Due to insufficient sample size, data are not plotted for IgG2 and IgG4. IgA patients could be separated by isoforms into IgA1 and IgA2, but no IgA2 patients were detected in this cohort.

TABLE 2 Statistical Evaluation of LC-MRM Performance in Separating Patient Groups. Monitored Corresponding Ig Diagnosis Other Diagnoses Statistical Results Protein(s) n Mean SD Median n Mean SD Median z-value p-value IgA1, 2 21 14.83 16.53 6.20 62 0.66 0.61 0.46 5.10 3.5E⁻⁷ IgA2 21 0.03 0.04 0.01 62 0.08 0.18 0.03 −1.36 0.17 IgG1, 2, 3 21 16.59 18.57 12.40 62 4.26 3.06 3.78 4.92 8.8E⁻⁷ IgG1 10 15.19 5.38 13.74 73 2.40 1.91 1.81 5.09 3.7E⁻⁷ IgG3 4 30.95 41.11 17.62 79 0.66 0.60 0.53 2.24 0.02 IgM 18 7.26 9.05 3.69 65 0.10 0.10 0.06 6.45  1.4E⁻¹⁰ κ KLC 36 11.99 11.09 8.83 47 2.37 1.72 2.04 6.16  7.2E⁻¹⁰ λ LC 36 12.00 30.00 1.75 47 0.44 0.63 0.22 5.66 1.6E⁻⁸ IgD 5 6.57 8.37 2.30 78 0.00 0.03 0.00 7.23  4.8E⁻¹³ Each immunoglobulin measurement is compared between the population of SPEP positive patients and patients with other diagnoses. For isoform-specific measurements, the diagnosis of the involved immunoglobulin is achieved solely by LC-MRM. In each case, the number of patients as well as the mean, standard deviation, and the median of the protein expression are listed. Statistical significance was assessed by the Holm-Bonferroni method; z-values and p-values are listed.

This additional information has the potential to improve patient monitoring, especially in cases of IgG MM where some isoforms are naturally high in abundance (such as IgG1 and IgG2) and others are significantly lower (IgG3 and IgG4). The patient's total IgG concentration may fall within the reference range for healthy controls (4.5-20 mg/ml), but a single isoform can be detected by LC-MRM and shown to be significantly overexpressed. For example, the total IgG was measured to be within normal limits for three patients, but elevated levels of IgG3 were detected with LC-MRM. This additional capability enables more sensitive detection of disease, and it also may implicate involvement of multiple immunoglobulins, which could indicate another clonal tumor population. As an example, 3 patients were found by LC-MRM quantification to have elevated IgG3 levels that were previously undetected (two in IgM patients and one in a patient not presenting with MM).

LC-MRM Quantification of Light Chains using Constant Region Peptides

In addition to monitoring heavy chains and their isoforms, LC-MRM was used to measure constant regions peptides as surrogates for the expression of the light chains, κ and λ, and to calculate a κ:λ ratio. Assays were developed for κ: TVAAPSVFIFPPSDEQLK (SEQ ID NO:9) and λ: AGVETTTPSK (SEQ ID NO:10). These measurements could be used to detect dysregulation of light chain expression not only as overexpression but also by the κ:λ ratio. LC-MRM data was not compared to the results of SFLC assays, because the values are expected to differ (due to the comparison of total light chain by LC-MRM to free light chain by SFLC). However, LC-MRM was effective in detecting light chain-only disease in all cases (4/4). Patients with light chain-only disease that could not be monitored by SFLC were not included in this study, so it is unclear if LC-MRM would have utility there.

To evaluate the separation of patients with κ and λ diagnoses by LC-MRM, box plots are shown in FIG. 3A and FIG. 3B, respectively. Statistical results are listed in Table 2. Protein expression levels in patients diagnosed with elevated κ were significantly higher than in other patients; λ levels were also significantly different in λ patients when compared to other patients. The κ:λ ratio values have been plotted in log-scale (FIG. 3C). Data from non-MM patients and those expressing biclonal light chains (i.e. both κ and λ) were not included, nor were samples (n=5) where only one light chain could be quantified. Out of the 30 K samples, only one patient was found to have a lower than expected κ:λ ratio (the reference range for total κ:λ in healthy controls is 1.3-2.7) (Katzmann J A, et al Clin Chem 2002, 48, 1437-44), and one patient had a ratio within the normal range. Out of the 30λ patients, two samples were found to have κ:λ ratios above the normal range, and two samples fell within the normal limits. Additional discussion on the characteristics of these patients is included in the supplement.

Longitudinal Patient Monitoring

An IgE MM patient was monitored using LC-MRM for comparison with existing protein-based methods (FIG. 4); total IgE quantification is more sensitive for disease detection than SPEP due to the low levels of background IgE expression (at μg/ml levels). Serum samples were acquired at diagnosis and each time the patient received treatment. Initially, LC-MRM and SPEP show a distinct M-protein correlating to IgE myeloma, assigned by IFE to confirm the SPEP diagnosis and by endogenous IgE peptide intensity in LC-MRM (FIG. 4A). However, analyses during the course of treatment illustrate the similarity of nephelometry and LC-MRM for monitoring IgE. SPEP results show no elevated IgE protein in the serum after the fourth and fifth cycles of treatment at 15 and 19 weeks after diagnosis (FIGS. 4B and 4C); nephelometry and LC-MRM were still able to detect elevated IgE levels at those time points (FIG. 4D). Compared with SPEP, nephelometry and LC-MRM can better characterize the disease in this IgE patient, demonstrating another decrease in tumor burden after the fifth cycle of treatment. After the sixth cycle of treatment and during the subsequent follow-up, neither method could detect IgE. Based on the clinical evaluation (and not LC-MRM data), treatment was discontinued after six cycles, and the patient has been in remission.

Detection of Variable Region Peptides for M-Protein Quantification

LC-MRM of constant region peptides has similar performance for detection of disease with similar intra-assay variability but higher inter-assay variability as compared with current immunoglobulin quantification techniques. One way to improve the LC-MRM method is to define the sequence of the variable region, which could lead to detection of the specific monoclonal immunoglobulin, similar to SPEP. De novo assembly was performed from RNA-seq data to determine the Ig sequence secreted by the H929 cell line. Although NCBI ORF Finder identified several potential constructs, a single protein sequence had the expected size and the expected constant region primary amino acid sequence. This amino acid sequence matched that expected from a translation of the IGKC, IGKJ1, and IGKV3-15 regions. Differences at the junctions were detected as can be expected during Ig recombination: proline was inserted between IGKV3-15 and IGKJ1, and arginine was inserted between IGKJ1 and IGKC. For the Igκ secreted by H929 cells, three constant region peptides (C) and 6 variable region peptides (V) could be detected by LC-MRM (FIG. 5). The peptides are: C1: VDNALQSGNSQESVTEQDSK (SEQ ID NO:14), C2: DSTYSLSSTLTLSK (SEQ ID NO:15), C3: TVAAPSVFIFPPSDEQLK (SEQ ID NO:16), V1: ATGIPAR (SEQ ID NO:17), V2: VTLSCR (SEQ ID NO:18), V3: LSVSPGER (SEQ ID NO:19), V4: LL(ox)MYDASTR (SEQ ID NO:20), V5: ASQSVSSHLVWYQQKPGQAPR (SEQ ID NO:21), and V6: LLMYDASTR (SEQ ID NO:22); the identity of each peptide was verified by comparison of RT and fragmentation with LC-MS/MS and standards. Because the specific amino acid sequences of the variable region peptides from monoclonal immunoglobulin may be contained in other antibodies secreted by different cells, the quantification of the disease-specific VRPs are limited by the amount of the peptide produced from the background of immunoglobulins secreted by normal plasma cells. Detection of the IgK immunoglobulin from H929 cells by LC-MRM of the LSVSPGER (SEQ ID NO:19) sequence in a background of serum from a healthy control could be accomplished over more than two orders of magnitude and down to a spiked level of 0.6 fmol/μl of serum, which corresponds to detection above background for 0.0015 g/dl. This value represents ˜67-fold improvement over the SPEP detection limit at 0.1 g/dl.

In addition, RNA-sequencing and in silico translation also provided the protein sequences of two K immunoglobulins from patients. Both patients are currently in remission, but serum samples were collected and analyzed with LC-MRM for variable region peptides. The first patient was IgA/K with a current M-protein measurement by SPEP of 0.2 g/dl, which is below the 0.5-1 g/dl level used to initiate treatment for relapse; the second patient has IgG/K disease with no detectable M-protein at the time the sample was taken. Therefore, three peptides from the κ light chain of Patient 1 were tested in both patients to see the specificity of assays for the variable region peptides (FIG. 6). In all cases, the level of each variable region peptide was at least 1000-fold higher in Patient 1 than in Patient 2. Based on these preliminary data, this approach could generate personalized assays for detection of tumor burden.

CONCLUSIONS

Using reference ranges for current protein-based assays, LC-MRM quantification of immunoglobulins was compared against current clinical methods using a sample size of 83 patients. While the LC-MRM assay is slower to run (overnight versus a few minutes), the therapeutic window for these patients is long, so treatment decisions do not have to be made immediately and the additional time required for this assay is not detrimental to the patients (Koomen J M, et al Mol Cell Proteomics 2008, 7, 1780-94). The ability of LC-MRM to monitor all immunoglobulins (and albumin as well as other proteins) allows for an increase in efficiency, with MM immunoglobulin and isoform quantification accomplished with one experiment (and one instrument). The LC-MRM method may improve analysis of the rarer MM types (IgD, IgE, and light chain only disease) that currently require multiple tests for monitoring. Peptide-based LC-MRM quantification of total immunoglobulin expression levels offers slight improvements in sensitivity over nephelometry, as well as the ability to quantify isoforms, with a trade-off in precision (˜2-fold higher CV values). For higher abundance immunoglobins (e.g. IgG1), the precision is the critical variable for detection of disease because of the background level of protein expression, which is a disadvantage for LC-MRM. For lower abundance isoforms and other immunoglobulins (e.g. IgD or IgE), an increase in sensitivity would be critical to detect low levels of tumor burden during treatment and relapse. The increase in sensitivity can also be used to monitor the amount of immune paresis (reduction in other immunoglobulin levels due to reduction of normal plasma cells from the bone marrow by the growth of the tumor), but this parameter is not currently factored into patient treatment decisions.

In this experiment, outliers in triplicate measurements were detected at levels of 6.4% or less; some peptides did not have any outliers detected. Reduction of CV values and elimination of outliers will be critical for clinical implementation without triplicate analysis. Automation of sample preparation may provide improvements in precision, and injection of larger sample amounts for analytical scale chromatography would be expected to improve on the nanoLC analysis here by eliminating saturation effects, improving precision, and eliminating outliers. If technology shifts to mass spectrometry-based methods, this set of assays could be clinically utilized. In order to pursue its implementation, a large cohort of healthy controls would need to be analyzed to define the appropriate reference ranges for peptide-based LC-MRM assays. Furthermore, additional data should be collected for longitudinal patient monitoring to define the levels of natural variation in immunoglobulin abundance in serum and to determine the threshold for increases in immunoglobulin level that should trigger additional treatment.

Finally, the determination of variable region sequences and the resulting tryptic peptides is a promising method for improving patient monitoring with quantitative mass spectrometry. Although this requires an initial RNA-seq experiment to identify the highly expressed rearrangements, these transcripts can be identified with as few as 20 million RNA-seq reads due to the high expression of Ig in multiple myeloma tumor cells. This method allows for a highly specific tracking of the disease-specific monoclonal protein. This personalized approach could offer a better understanding of the unique aspects of an individual patient's disease, but the effectiveness of the assay would vary between patients because of the sequence-specific performance of the variable region peptides and the patient-specific background of other immunoglobulins with the same sequence.

An assay platform that measures both constant region peptides for all immunoglobulins and variable region peptides for the patient's disease-specific immunoglobulin could significantly improve on sensitivity. The detection of the disease-specific biomarker is then paired with the ability to detect changes in the other immunoglobulins, which could indicate immune paresis (describing disease severity) or expansion of another MM clone that secretes a different immunoglobulin (i.e. relapse with a different MM tumor). This platform would be of use in monitoring depth of response to therapy, which has prognostic value, and determining disease progression either from premalignant conditions (e.g. MGUS) or in relapse after treatment. Improvements in the ability to quantify the tumor burden are likely to shape novel clinical approaches to MM treatment.

Example 2: Assay Development Using LC-MS/MS of Serum at the Time of Diagnosis and De Novo Peptide Sequencing to Determine Variable Region Peptides

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) peptide sequencing can be used for the detection and identification of variable region peptides (VRPs) in serum samples or enriched Ig fractions. Unlike the sequencing of antibodies with affinity capture using a known antigen, separations methods are used to create fractions of total Ig, and the expression level of the monoclonal Ig specific to disease will need to be sufficiently high to make the VRPs obvious.

Sample Selection for De Novo Peptide Sequencing

In order to test the potential of LC-MS/MS to define VRPs for assay development, serum from 10 of the 30 patients in Example 1 with varying expression levels (1 mg/ml to >20 mg/ml) are blinded and used for testing the effectiveness of VRP detection by LC-MS/MS.

De Novo Immunoglobulin Peptide Sequencing

Because of the wide range of expression levels different methods for identifying variable region peptides from the monoclonal Ig can be employed. When the expression is very high (e.g. >20 mg/ml or 25% of total blood protein), tryptic digests of total serum proteins can be compared to isolate unique peptides in each sample. However, when the expression is lower, the monoclonal Ig will need to be enriched. For that purpose, gel-based SPEP is used with excision of the γ region or SDS-PAGE with excision of heavy (50 kDa) and light chain (25 kDa) bands prior to LC-MS/MS. For IgG, enrichment with immobilized protein A/G (Ultralink, Pierce) is used for enrichment. All samples are denatured (8 M urea), reduced, alkylated, and digested with trypsin. LC-MS/MS is performed with UPLC (RSLC, Dionex, Sunnyvale, Calif.) and high mass accuracy MS and MS/MS in an hybrid linear ion trap-orbital ion trap mass spectrometer (LTQ Orbitrap, Thermo, San Jose, Calif.), as described previously. Peptide sequences are identified by database searches with Sequest (Thermo, San Jose, Calif.) and Mascot against the human entries in the UniProt database containing both forward and reverse protein sequences to enable assessment of false discovery rate (% reverse out of the total). Scaffold will assemble data to define and eliminate the common background.

For the samples with the highest abundance Ig expression, SIEVE is used to compare replicates of one sample against all others to find unique peptides, which are manually sequenced de novo using high resolution and accurate mass MS and MS/MS data. In addition, ScanRanker is used for sequence tagging, identifying peptides using the MS/MS data first. Comparisons of these results between samples indicates the unique peptides in each sample. Finally, conserved amino acids and sequences in the variable region of the immunoglobulins are used to search for patterns in the MS/MS data or for peptides with specific cleavage sites (and therefore specific C-termini) These strategies are applied to raw serum digests and enriched Ig fractions to define the amount of Ig expression required for each method to be effective. VRPs detected by LC-MS/MS are compared to the RNA-seq to determine the ability to develop these assays from serum without the need for bone marrow.

Example 3: Determination of the Sequence of the Immunoglobulin (Ig) Secreted by the Multiple Myeloma Tumor Cells Using RNA-Sequencing (RNA-Seq) Using CD138+ Cells Selected from Bone Marrow Aspirates

The example data involved 100 base read lengths (e.g. HiSEq, Illumina), but longer read lengths produced by other instruments (e.g. 300 base reads with MiSeq, Illumina) would be advantageous for data quality. Attempts are made to reconstruct the heavy chain constant regions (IgG1-4, IgA1-2, IgM, IgD, and IgE), the light chain constant regions (Igκ and Igλ), the joining regions, and the variable regions for each immunoglobulin. Successful reads should assemble constant region, joining region, and variable region for the intact immunoglobulin. Both heavy chain and light chain can be important for patient monitoring.

mRNA enrichment can be used to improve the application of sequencing and reduce the total amount of sequencing required for each patient.

5′ RACE can also be used for targeted sequencing to increase the number of reads for the immunoglobulins and decrease the overall need for sequencing per patient. Briefly, since the constant regions of the antibody are at the C-terminus, primers to the beginning of the C-terminus of the constant region can be used to read back through the joining region and the variable region. Primers can be designed against the heavy chains and their isoforms as well as the light chains and their isoforms.

Data from the above methods are assembled and translated to protein. The protein sequence is used to define peptide biomarkers that can be measured with quantitative mass spectrometry. The Ig sequence is blasted against existing publically available databases and previous patients to define the most unique parts of the sequence.

The Ig sequence is digested in silico to generate peptides that contain the maximally unique sequence. Multiple enzymes are tested, including but not limited to trypsin, endoproteinase Lys-C, chymotrypsin, endoproteinase Glu-C, Asp-N, Arg-C, etc. The effectiveness of the peptide lies in its uniqueness and its ability to be detected by the mass spectrometer.

Heavy and light chain proteins are isolated by SDS-PAGE and excised for in-gel digestion. Alternatively, the filter-aided sample preparation (FASP) can be used for in-solution digestion, if enzymes perform poorly for in-gel digestion.

Liquid chromatography-multiple reaction monitoring mass spectrometry (LC-MRM) is used to screen for constant region and variable region peptides. Standards are then synthesized for the endogenous peptide using stable isotope-labeled amino acids or single conservative amino acid replacements and characterized by LC-MRM to test assay sensitivity (LOD, LLOQ, ULOQ), linearity, accuracy, precision, and other figures of merit.

For peptides with highly unique sequences but poor response in the mass spectrometer, chemical labeling with tandem mass tags (TMT, Proteome Sciences) or tags for relative and absolute quantification (mTRAQ or iTRAQ, ABSciex) are applied to enhance the signal for those peptides. As needed, enrichment of the immunoglobulin light and heavy chains are achieved by SDS-PAGE, MW fractionation, or affinity pulldown.

Biomarkers are applied to patient samples to measure disease burden. LC-MRM is used to quantify constant region peptides to measure the total class of each immunoglobulin and its isoforms. The exact peptides depend on the enzyme selected. Examples for trypsin are provided on the following pages. LC-MRM is also used to quantify variable region peptides to measure the disease-specific immunoglobulin. Alternatively, LC-MS/MS or pseudo reaction monitoring (PRM) strategies can also be used.

Quantification of the disease-specific peptides can be used to define patients progressing from pre-malignant conditions, measure response to therapy, and detect relapse.

Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference.

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims. 

What is claimed is:
 1. A method for monitoring a plasma cell dyscrasia in a subject, comprising: a) treating a biological sample comprising immunoglobulin from CD138⁺ plasma cells from bone marrow aspirates from the subject to enzymatically cleave target immunoglobulins, wherein the target immunoglobulins are IgG, IgA, IgD, and IgE heavy chains, into variable domain peptide fragments of the target immunoglobulins; and b) measuring the variable domain peptide fragments in the sample by quantitative mass spectrometry to quantify the amount of each of IgG, IgA, IgD, and IgE heavy chains in the sample using multiple reaction monitoring (MRM); wherein the plasma cell dyscrasia is monitored by the amount of the target immunoglobulins in the sample.
 2. The method of claim 1, wherein the variable domain peptide fragments are first identified by a method comprising: a) determining the amino add sequence of the target immunoglobulins; and b) identifying in silico variable domain peptide fragments formed by enzymatic digestion of the target immunoglobulins that: i. contain amino add sequences from the variable domain of the target immunoglobulins that are sufficiently unique to distinguish the target immunoglobulins from other immunoglobulins in the biological sample, and ii. are capable of being detected by a mass spectrometer.
 3. The method of claim 2, wherein the variable domain peptide fragments contain the complementarity defining region (CDR) of the target immunoglobulins.
 4. The method of claim 2, wherein the amino acid sequence of the target immunoglobulins is determined by a method comprising: b. RNA-sequencing immunoglobulin mRNA from a plasma cell of the subject that is associated with the plasma cell dyscrasia; and c. in silico translating the RNA sequence of the immunoglobulin to protein.
 5. The method of claim 1, wherein the plasma cell dyscrasia comprises a multiple myeloma, and wherein the method monitors tumor burden in the subject.
 6. The method of claim 1, further comprising measuring in the sample after enzymatic cleavage one or more constant domain peptide fragments containing amino acid sequences from a constant domain of the immunoglobulins to quantify total immunoglobulins in the sample.
 7. The method of claim 6, wherein the plasma cell dyscrasia is monitored by the ratio of target immunoglobulins to total immunoglobulins in the biological sample.
 8. The method of claim 1, wherein the target immunoglobulins further comprise human kappa light chain or human lambda light chain.
 9. The method of claim 1, wherein the plasma cell dyscrasia is multiple myeloma or monoclonal gammopathy of undetermined significance (MGUS).
 10. The method of claim 1, wherein the peptide fragments are measured by spiking in during the mass spectrometry a known amount of the one or more peptides containing a specific label.
 11. The method of claim 10, wherein the specific label comprises a heavy isotope label or an amino acid substitution sufficient to create a detectable mass difference.
 12. The method of claim 11, wherein the heavy isotope label is ²H, ¹³C, or ¹⁵N.
 13. The method of claim 1, wherein the immunoglobulin in the sample is denatured prior to enzymatic cleavage.
 14. The method of claim 13, wherein the immunoglobulin is denatured by treatment with urea, disulfide reduction, and/or cysteine alkylation.
 15. The method of claim 1, wherein the immunoglobulin in the sample is enzymatically cleaved by proteolytic enzyme digestion.
 16. The method of claim 15, wherein the proteolytic enzyme is trypsin.
 17. The method of claim 1, further comprising a treating step to isolate the target immunoglobulin prior to enzymatic cleavage, wherein the treating step comprises one or more of size exclusion chromatography, gel electrophoresis, and/or affinity chromatography.
 18. The method of claim 1, wherein the mass spectrometry comprises liquid chromatography coupled to multiple reaction monitoring (LC-MRM).
 19. The method of claim 18, wherein the mass spectrometry is conducted on a triple quadrupole mass spectrometer.
 20. The method of claim 1, wherein the method is used to monitor for progression of monoclonal gammopathy of undetermined significance in the subject to multiple myeloma or relapse of disease after prior treatment.
 21. The method of claim 1, wherein the method is used to monitor the efficacy of a treatment regimen on a subject with multiple myeloma or MGUS. 